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Old 06-24-2011, 01:50 PM   #16
rizzer OP
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Deminimis and Pookiebear, yeah I think you're right. It's function over everything else anyways, isn't it?

should be cheap to pick up a honda GL series back home...would be round £500.
like this one:

which I think has the same (or similar) engine as an xr200

ideas are starting to creep in
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Old 06-24-2011, 02:05 PM   #17
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I can't tell from that pic, but it kinda looks like that bike has a perimeter or backbone frame. You want a frame under the engine (cradle frame), in my opinion.

Another bike you may wish to consider is an old Honda XL. I mean old XL (70's-80's). The world was lousy with them, so you may have good luck sourcing one on the cheap. Good reliable power plants. Kinda heavy, but stripped down, it might just work well. My first bike (that I owned) was a '74 XL100. Beat that thing like a red-headed stepchild. Nearly bombproof. Perhaps more of a scrambler style, but it might work. For example:


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Old 06-24-2011, 04:16 PM   #18
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Originally Posted by rizzer View Post
Deminimis and Pookiebear, yeah I think you're right. It's function over everything else anyways, isn't it?

should be cheap to pick up a honda GL series back home...would be round £500.
like this one:

which I think has the same (or similar) engine as an xr200

ideas are starting to creep in

Yep,I'd convert that,Find some dirt bike forks with about seven inches travel,lay down the rear shocks a bit to soften the rear action,position the upper mounts to also raise the rear up to match the longer forks. Move the footpegs to a location about three inches behind the swingarm pivot,mounting them as low as possible. Gut everything you can off of the bike. Vintage minibike or moped gas tank.Flat thin pad for a saddle. Hopefully a 4.00x18 trials tire will fit(I'd make that a prerequisite for the project) fit a 21 inch front,keep a disc front brake. Try to go for a vintage look but with more rear wheel travel. Maximize your steering lock as much as possible. fab a tough skid plate. build a high pipe.sounds like fun!
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Old 06-24-2011, 04:27 PM   #19
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Deminimis, ah you're right about the frame. too bad XL's are rare back home :/
the small population around are prolly in collector's garages. historically we had honda CG's, then the small CB's (100-125, and a tiny amount of CB200's), then the GL's (150-200). I think none of them had double cradle frames.
I had a tiger (GL200) about 5-6 years ago and can say that the engine and electrics were pretty much bulletproof. would be a pretty good base engine for a start. best of all is that it's cheap...but then again will need to get the frame modified. should be easy to extend some pipes under the engine

there is a pretty good supply of KZ200's for dirt cheap, and I think they had cradle frames. but the spareparts availability would throw me off though

I was also thinking of getting a cheap liquid cooled cub bike (yamaha LC135) and strip the engine. would cost about the same as the honda tiger buy used but at 5 years younger. the displacement is only 135, but there's a good supply of bore up kits from Taiwan and Thailand that'll get it up to around 175-180cc. not much, but would that be enough for a little "play bike"?
say with a 16' rear and 19' front and low gearing?

Dmay, yeah and it looks like it won't be too much work/budget. can't wait to get home!!!!

thanks for all the inputs guys, I got a whole lotta options on my plate right now...constantly browsing used bike forums and what not
keep 'em coming though, we ain't done yet!

edit: my wife's gonna hate me when I start leaving the house to hunt for a bike and parts on my arrival heheh...

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Old 06-24-2011, 04:35 PM   #20
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Dmay, couldn't help notice you got a TY in your sig. how's the engine like? I mean does it share resemblances to RX's or DT's? or other yamahas?
would be cool to look at a 2 stroke options as well
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Old 06-24-2011, 04:43 PM   #21
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Rizzer's home made picture looks awesome! If you can fab up something like that you'll have a bike that'd be competitive in the lower levels of modern events at the very least.

You could definitely make that fun to ride. For specs just search online for dimensions etc of any modern trials bike - Gasgas, Ossa, Sherco, Scorpa, Montesa etc.

I wouldn't worry too much about a cradle frame (I don't think any modern bikes use full cradle frames - I know my Montesa doesn't). The engine really isn't the big concern, just get something light. Focus on the chassis.

You really need an 18" rear wheel as that's the only size trials tires come in and they are rather unique. A 21" front would be good too, but a proper trials front is less critical. A knobby front would work fine for most stuff.

Regarding the two stroke engines and exhausts they are tuned to run well at very low rpm and be very controllable. They aren't especially powerful. I think my liquid cooled, 250cc two stroke makes about 17hp. IIRC it actually has a rather short stroke as compared to my CR250R motocross bike. I'm not sure why this is,but it works out ok. It may simply be to keep the engine dimensions smaller.

The exhaust is very critical on a two stroke to how the engine runs. There's a whole literature on exhaust tuning and design - you'd want to read up before building a system I think. I don't have a quarter the knowledge to design my own expansion chamber. I will say that on a trials bike exhaust design looks to be driven mostly by packaging requirements and only secondarily by performance requirements.

Engine performance really isn't a big deal. You need very little power. What you need is a really compact bike, light weight bike with a controllable engine and super-low gearing. A 100cc-ish two stroke would be fine. Folks do all sorts of amazing stuff on 125 and even 80cc trials bikes with no issues - just run a bit lower gearing and rev the motor more.

I've known folks to take bikes apart and put them in their airplane luggage. Would that be illegal for your country even if you won't be registering the bike for road use? Here you can realistically do most anything you want as long as its only used off road "closed course" only. In '97 when the honda CR250R was available in Japan but not the US the editors of Dirt Rider magazine flew to Japan, bought a CR250R, took it apart in the parking lot and brought it home on the plane in their luggage. They published the whole story with tons of pictures - good fun

I have an '01 Montesa Cota 315R and it works well enough for me. They are about 1k pounds in the UK.

lamotovita, D6 as in AMA District 6. I am moving up next event (I've only been at this for a couple of months so started out only one class up from the bottom - cleaned the whole day). I certainly couldn't clean a novice D6 section on a non-trials bike, but I couldn't even ride around the section with a whole bunch of dabs. I'd probably have to get off the bike and drag it around corners or make a 30-point turn or similar. Many sections are pretty darn tight. A few are more straight and wouldn't be hard on a big bike and one was really straight and rocky and would have probably been easier on a big bike

Maybe your novice is more like our vintage-novice - that I could defo ride on a dirt bike as its a much less tight course - or maybe I just suck.

Anyway, I totally agree that you can have a ton of fun doing technical, trials-ish stuff on a dirt bike.

wet rocks


Steep ledges (this was part of an old trials section)


Dry rock


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Old 06-24-2011, 05:01 PM   #22
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I think, your best bet is it get a trials bike, modify it back to whatever trail ridng you wish to aim for, best bikes for this are the pre 2000, for the gasgas models, IMHO. probably at least that era form most bikes produced then.

Gasgas made (so very few) true trials/trail bikes where they used a top of the frame, gastank and seat for a MX type; bike married to the neck and engine parts of a frame and suspension for a trials bike. That was in 96-98 called the Pampera. I dunno how many made it to the US or canada either. there was a 329 model and 250, last ones were grey, early ones were red and photograph in used condition as PINK, lol. BTW, not that long ago, there was one forsale on gasgas.com.

problem is, AFAIK they arent good for either use, the fork rake that is used in trials, is scary at motocross speeds, the supension and frame is lightweight, so I wouldnt enter a stadium cross that is for sure. but I still would own one, I would love to play as I drive to work, in places I probably shouldnt even be thinking of tresspassing on.

Oh, BTW, I have the honda tlr200 (Reflex) and is was more trialsy for that moment in time (86-87). the newer than that era, but older BETA ALPS would be cool as well.

Sherco I thought (via scorpa?) was going to produce a more trials "ish" trail/enduro bike, but AFAIK never took off this last year? or still in developement? Hoping to dominate the enduro cross or something, {excuse my weak memory on this subject, I have general idea of what I may think i read here...) and i assume new prices would be near $8,000 so not the bargain you are probably hoping for.

Try to find a reflex, if nothing else it will make a really nice girlfriend bike, or a potty bike, as I call it, in stock form, not terrible (twinshock type application) with some serious mods.

Search for ITSA (internation twin shock association, I think it is... then you might find more conversion bikes?

But Modern, I just think you would work your but and wallet off, then be handicapped and discouraged if any perception was to use it for trials...

Moto Trials, that it is called now, is at a brink, where they might have to adopt an "enduro" specification class type bike, so we can convert more fellas like you. or at some point (which will never happen I bet) to de-evolutionise the bikes they use for modern trials.

Problem is, the sport is ran and lives (die hard) due to people who eat and sleep trials. MX is the same, the pro's are what at least the 5% that grow up to compete at that level, aspire to day in day out. if they didnt, when things get hard, or weather is not perfect, nobody shows up for an event, or for that matter in trials, will bother to set one up. the guys that would like (actually think they would like) to just come and "putter around on it" always find excuses to not make it to the events, be it "football season, so sunday's out" or kid has x... or old buddies are headed to the hills/racetrack.

I been doing trials for over 30 years, we have to get up at 5 am and make the drive (all Year round, in Kansas) to compete that sunday morning. Ive had 30 riders watch the news, on friday night with forcast for cold, hot, rain, or what have you, and even we left the house in a respectable storm, to end up with the nicest dayfor a trials at the site 177 miles south of my home. My folks, pop who is 75 and still competes, has made this our family outing all these years, for the most part. but my buddies, who have wives and kids that avoid the motorcycle stuff, dont ever make it more than 14 months, because they cant go out with the wife all night sat night, then get up and go, and meet thier own hopes of beating the rest of the families that accept that way of life, lept well last night and cleans thier clocks!

that is dedication, spirit of competition, and love of the fun we have on a trials bike... I can practice for an hour in my 2car wide driveway, and have even more fun, with less than most suburban back yards to practice in/on all week leading up to the event!

Anyway, if the market nich you are trying to sell to, doesnt do the above, realistically I think that might be why there isn't a bike like you are thinking of, as most anyone who knows business, don't see a real market for them!

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Old 06-24-2011, 07:35 PM   #23
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Dmay, couldn't help notice you got a TY in your sig. how's the engine like? I mean does it share resemblances to RX's or DT's? or other yamahas?
would be cool to look at a 2 stroke options as well


TY350 is like a YZ/IT engine from the early eighties,the last air cooled Yamaha offroaders,unique bore and stroke,massive(too much!) flywheel

A DT125/DT175 could be a good candidate if you can get the front end rake pulled in to about 23-25 degrees.
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Old 06-24-2011, 08:13 PM   #24
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Old 06-24-2011, 08:25 PM   #25
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BikePilot, thanks a lot for the post :)
there'll be a lot of technical aspects I'd need to cover to plan my build. it's at least comforting to know that I won't have to prioritize for large displacements. I was looking at a Gas gas street legal bike (forgot the name) that was only a 125cc 4 stroke and it made me think I got a good chance
I was particularly interested in the exhaust of the 2 strokes and the effects of it towards the power band. I mean you can barely see any expansion chamber there. I'll probably need an engineering course to understand that though heheh...
and a 250 smoker with a 17 hp? must have a crazy amount of torque for trade-off. would love to know how it rides

about taking engines apart. I still doubt it'll pass customs, cause even if it's not going to be for street use, there's a bullshit stigma going around in the law enforcements there that all bikes without papers are assumed to be stolen which makes the owners suspects of GTA. and the government have even made things tighter by banning engine and frame imports. but to be honest, the bureaucracy is too complicated for me to understand and will need a whole new thread just to discuss it hahaha...

Sting, yeah the truth is trials has little to no market in Indonesia and it isn't covered (or even recognized) by the national motoring association. there is a little trials event that a cigarette company runs but it's purely for entertainment purposes.
http://www.youtube.com/watch?v=VO8D7uybrmE
and I've only recently found out that there are little bike clubs strictly for trials. other than that, the major consensus don't even know what a trial bike is. they'll be amused by it not having a seat, but other than that there's no meaningful market interest. so yeah, there's basically no motive for a trial producer to sell out there :/
I'll be happy enough just to have a home-made trial bike to have fun with :)

Dmay, realistically speaking, and RX engine would be easier to maintain as DT's spares are no longer widely available. but I'll look for a comparison of the two. btw,the pic of the bike I posted earlier was from an RX. It can take an air-cooled YZ125 head without needing to mod.

Lamotovita, whoa is that a S90? wicked cool!

btw fellas, since I already have forks from a KTM525, will that be good for a trials bike? I mean the size/length and all...it is a bit bulky though

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Old 06-25-2011, 01:53 AM   #26
Pete-NZ
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Quote:
Originally Posted by rizzer View Post

and found a home-made trial pic
looks like an engine from a yamaha RX-135 or RXZ-135
and the white yammie behind it looks cool as well
The white yammie in back..
looks like a late 70s vintage TY50 or 80...
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Old 06-25-2011, 04:42 AM   #27
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The custom made T.K.R.J. looks great, this bike is really cool!
The frame geometry is up to date, to the motor I have not seen
this engine here or heard anything about the RX model.

The threat questioner should tell us probably something about his manufactoring skills too, then it would be easier to post a good hint.
(I have a lot of respect about the improvisation skills the folks have in asia).

Starting trals with an modern enduro like bike is IMHO not a so good idea,
the frame geometry and engine power output is too different. If you have many skills and some machinery it is possible to create a trials machine of
an modern enduro engine:


But even the frame work needs a lot of machinery work to get a good result:


Then you have to make a lot of changes to the gearbox and the
power delivery too.

To rebuild an older engine is IMHO easier, also to build or modify a standard tube frame, like this Stornello engine of the beginning 70's
with a home made frame:



I would try to get one of the already mentioned Yamaha DT 125cc from the 70's to 80's models that may be even available in your home country
and take that model as a start. Any trial specifiec parts you can take from a TY 125 or 175cc model. These bikes or parts to this bike model are easy to get in the UK and not very expensive.

The 125cc TY:


Later on you can rebuild this bike with a 175 or 200cc cylinder/head/piston and do some small other changes too, (chopping of
parts that you don't use for trialriding, ...)

The result can be something like this:


Very competive even nowadays!
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Old 06-25-2011, 08:27 AM   #28
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Your KTM forks could work - they are really overkill and the biggest issue I expect you might have is that they will be a bit long and large in diameter (which might limit turning radius). They are certainly strong enough though. all current trials bikes use fairly skinny conventional forks to maximize turning radius. If you use the KTM forks consider finding the softest springs you can and run very light weight oil (maybe 2.5wt) at a very low level. You might even try them with a spring only in one leg and damping only in the other leg.

The torque on a modern trials bike isn't all that impressive really. They scoot ok off the bottom, but I doubt they really make a whole lot more power from low rpms than say a 250cc two stroke MX bike and they might actually make less (the gearing is so dramatically different its hard to tell - 4th on the trials bike is probably something like 1st on my CR). Main difference from a MX bike is that the trials bike runs really clean and smooth from very low rpms where the MX bike would be unhappy, blubbery and prone to loading up and fouling. The trials motor is ultra-controllable with smooth, clean, linear response. Its all about control, when you have super-low gearing and a 160lbs bike, you don't need much power at all. Also the flywheel is very heavy so if you need a quick burst of power you just get the flywheel spinning (rev the motor) than take advantage of some of that stored energy in the flywheel. If you watch a video of a pro doing a big splatter, especially on a 125cc bike, you'll note that the rider revvs the motor out very high with the clutch in before doing anything. When you've got a heavy flywheel spinning quickly you can dump an enormous amount of power into the rear wheel for a quick burst.
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Old 06-25-2011, 08:31 AM   #29
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One more thing, to get an idea of what people normally do with trials bikes (youtube videos of pros really isn't very relevant to what mere mortals can manage ) and how we do it, start going through some of these tutorials. I think it'll help you get a better understanding of what the bike needs and doesn't need
http://trialstrainingcenter.com/how-...-to-tutorials/
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Old 06-25-2011, 11:46 AM   #30
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Pete, thanks for the info. I didn't know they existed in our market :/

PScrauber, yeah, I don't think I can afford to go through that length of total frame rebuild as your pics showed. would prolly opt for a more chop approach than fabrication. your TY example is a much more convenient option for me. btw, man that yellow TY is pretty!

also, the RX-135 (AKA RX-King) in its standar form:

there's also a Z version:


the king version is infamous for being getaway vehicles for criminals. and being a bulletproof engine with low maintenance costs, it was also widely used for bike taxis. also, the gearing on the king is lower than the RXZ. another plus of choosing this engine is that 2 stroke value has gone down in recent years so it should be pretty cheap.

Bikepilot, thanks for the link! that's gonna help me get through the sleepless nights heheh
I agree about the suspension though, I also think it could be overkill to use the KTM fork. would make more sense to get a smaller/skinnier conventional fork from the KLX150 for example.
I read somewhere that trials forks are "springy", and you said it should be soft. does this springy means more preload than damping? and would soft means more tendency to bottom out kinda soft?
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