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Old 03-01-2013, 01:31 AM   #14146
robmoto
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Quote:
Originally Posted by motolab View Post
Which brand(s) of aftermarket stem seals have you tried?

Regards,

Derek
Derick carn,t help you much, I bought a after market top end gasket set from Italy on Ebay and thought or a bonus valve stem seels included.
Suzuki don,t include them with there gasket sets.
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Old 03-01-2013, 04:31 AM   #14147
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Quote:
Originally Posted by robmoto View Post
Derick carn,t help you much, I bought a after market top end gasket set from Italy on Ebay and thought or a bonus valve stem seels included.
Suzuki don,t include them with there gasket sets.
Could the brand been Athena?

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Old 03-01-2013, 10:17 AM   #14148
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Cool2

The spring is finally here... 10-12 degrees Celsius and the sun is brighter than ever
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Old 03-01-2013, 10:54 AM   #14149
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Folks, I'm on the scrounge. Has anyone an unwanted right-hand drive headlight? Daisy is an import from Germany and is fitted with a left-hand drive headlight, the MOT testers are getting a bit more anal.

If anyone can help I'm happy to cover all costs.
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Old 03-01-2013, 11:58 AM   #14150
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Here a list of bits i would like to replace on my 750 with ones that are in a better shape ,so if you have any of them please PM me ,thanks
A UK spec headlight ,i have 3 lights but all off euro models MOT here is a bit stickey about the headlight beam.
A set of MPH clocks ,even a trashed set i can nick the MPH dial off would do as again MOT here doesn"t like KPH clocks
A decent front and rear disc ,the ones i have are worn so a better set would do the job.
Thanks
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Old 03-01-2013, 01:14 PM   #14151
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missing rubber seals...?

Hello friends!
My front brake was sticking this morning, and it made me fall over on some wet road-markings. So I took the calipers apart and, correct me if I'm wrong, but should there be rubber o-ring seals in this picture....?
If so, anyone know where I can get a set?
Thanks!
Pete

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Old 03-01-2013, 02:54 PM   #14152
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You can find all you need from Mr. Hesslers DrBig website.

http://www.dr-big-shop.de/

Robs.
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Old 03-03-2013, 08:49 PM   #14153
Ladder106
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Quote:
If so, anyone know where I can get a set?
Standard Suzuki parts would likely be your best bet here the seals come as a set, I believe.

If your pistons are as bad as the one in the photo, I'd suggest replacing those also. The one I can see looks pretty well done for.
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Old 03-03-2013, 09:32 PM   #14154
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Quote:
Originally Posted by Ladder106 View Post
Standard Suzuki parts would likely be your best bet here the seals come as a set, I believe.

If your pistons are as bad as the one in the photo, I'd suggest replacing those also. The one I can see looks pretty well done for.
If there is corrosion (i.e. brown colored buildup or a dull grey color rather than a bright "as machined" look) in the seal grooves (check the portions hidden from normal view with a dentists mirror), replacing seals and/or pistons will not help.

Regards,

Derek
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Old 03-03-2013, 10:01 PM   #14155
Ladder106
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More Air = More Fuel

Sounds simple, right? Got MORE AIR, well...just add more fuel and everything is happy.

The basic concept is sound but finding the place where everything is Juuuuust Right is a bit more difficult.

WARNING:
This is likely to be a long post so if airbox mods and jetting is not your particular interest just go on to the next post.


This whole thing started when I transplanted a SR43 engine into a SR41 frame. I needn't go into the reasons for this mad scheme but I did it so that was the beginning.

What I found was a motorcycle that wasn't very happy and wasn't making me very happy either.

The first thing I learned is that you don't get a SR42 but just sticking a 800cc engine into the SR41. The primary gearing is different and while you get the extra cc's you also get a bike that's geared quite high.

What I found was an engine that vibrated....a lot. More than I though was reasonable. First thing I did was to replace the balancer chain with a shiny new Suzuki part. That only made it sound smoother but didn't do much for the way it ran.

NOTE: The bike is running with a 1000 cc GSXR silencer and standard Suzuki header pipe. I like the silencer tremendously for it's sound, fit, and the ability to accept a spark arrestor that will allow me to legally ride off-road in California. NO SPARK ARRESTOR AND MR. RANGER CONFISCATES YOUR BIKE....THEY ARE SERIOUS.

It seemed that the engine wanted more air. So, my first step was to open a hole in the side of the air filter cover. I didn't want to loose the rubber snorkel at first so I removed as much material as possible leaving the snorkel in place.



This made an obvious change in the way the bike ran. It was now surging and not running at all well about 3800 rpm or so. In any gear above that engine speed it would surge and would not be coaxed to pull over 4500. At the point it started surging I pulled the "choke" and the bike ran better. Not great but improved. My deduction was....more fuel.

Figuring that if it was lean at mid-range, it would certainly be lean on top I elected to increased main jet sizes rather than just raising the needle.

With a pair of 125 main jets installed and the filter lid as shown above, the bike ran quite well. It would pull top revs in all gears but would still not pull past about 5000 in top. I felt there was maybe more to be had so I opened the air filter lid as much as possible.



Another test ride proved that more air was indeed getting into the engine since the dreaded lean-surging was back. It moved up the rev-range to the 5000 rpm level but the bike would not pull over 5500 or so in the lower gears.

So....more gas, right?

Next step was a pair of 130 main jets...............
...............and manged to move the surging a bit further up the rev range to 5500 with no pull over 6000. This time I went out with a roll of trusty Duct Tape. After a bit of fiddling about I got the bike to run really well (according to my butt-dyno) by sealing off a bit of the open air box. Thusly:



I would have left it here but felt like I owed it to "science" to find a point that the bike would run well with the entire filter lid opened.

So....even more gas? You betcha.

Installed 132.5s. (Notice how I'm creeping up on the problem).........
........Getting closer. A hint of surging at 6000 in lower gears but still not pulling over 5500 or so in top


Gotta keep going, so even more gas?

My shop did not have any 135s available so my next step was 137.5........
........That DID IT. I was there......almost....because another problem had reared its head.

AIR FLOW PAST THE HOLE: or the Bernoulli Effect, Pricipal, Law....thing

With the pair of 137.5s installed the bike would pull top revs in all gears except the top part of 4th and 5th.

With the SR43 primary drive and geared 15/47 at the final, the top of my 4th gear is over 85 mph.

At this speed air was not flowing into the airbox as it should. By putting my hand in between the tank and the side panel and blocking the air directly in front of the filter, the bike picked up revs in 4th and ran better in the top part of 5th.

Thinking that riding close to the TON on knobbies with one hand on the bars and the other stuck into the left side of the bike was a bit mad, I felt I had proved my point and set out to build some sort of "air-dam" or reverse-scoop to shield the intake a bit.

Using my 3rd grade arts-and-crafts training I cut up a small plastic water bottle and stuck it onto the filter lid with Duct Tape (what eles?)

Promise not to laugh, please. It's what they call "proof of concept" or something in the engineering labs. It wil be replaced in future with something much more permanent.




It's crude, but, HEY....It worked. Pulled top revs in 4th and 6500 in top gear before the pavement ran out. Performance in the lower gears felt the same so I don't think I'm restricting the air flow down low. it just needed protection at higher speeds.

As of this afternoon, I have refilled the tanks with Premium Fuel (yes it's still our E10 rubbish) and will now ride the bike in a sane "normal" way to see how I'm doing for milage/efficiency.


This leads me to a recent post from Derek at motolab (no caps in the name, i checked). motolab (http://www.moto-lab.com/) is about 80 miles away from me but because I'm such a stubborn,lazy sod I have not been down to see him yet. Once I get this bike as sorted as I can, I plan to go down there and let him plug it into a wall and have a go at it with all the latest machines. This way he can tell me that everything I've done to date has been rubbish and we can both have lunch and a laugh.

Anyways....here's Dereks post from the Pre 96 DR650 Thread on ADV.

Quote:
Indeed, but be aware that the main jet then required to make the mixture correct during WOT high rpm operation may produce an inordinately rich mixture at lower rpm. This can be compensated for via a larger needle base diameter, smaller emulsion tube, lowered fuel level, or a combination thereof. Depending on the shape of the fuel delivery curve, it may also be possible to reduce the main air correction and then install a smaller main jet.
So my question to Derek is:

What's the next step? Lower the fuel level in the bowls, or raise the clips and drop the needles?

First answer: Stop fumbling about, come to the shop so we can see where you are and find out where you want to go.

I know this, but if we can assume I wont do that right away, what would be your next step?

Over to you at motolab........................................... ........

Ladder106 screwed with this post 03-03-2013 at 10:09 PM
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Old 03-03-2013, 10:24 PM   #14156
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Quote:
Originally Posted by Ladder106 View Post



It's crude, but, HEY....It worked. Pulled top revs in 4th and 6500 in top gear before the pavement ran out. Performance in the lower gears felt the same so I don't think I'm restricting the air flow down low. it just needed protection at higher speeds.
Is this dam forward or rear facing?
Quote:
What's the next step? Lower the fuel level in the bowls, or raise the clips and drop the needles?
Before anything else happens, you must first make sure that main jets are installed that are correct for the leanest area of the fuel delivery curve for WOT. Then you would see at what rpm the richest area is, and by how much it is too rich. Next comes a judgement call to determine whether a uniform mixture across all rpm at WOT can be achieved via a change in needle shape, emulsion tube size, fuel level and/or main air correction. Some of the the decision-making process may well be predicated on parts availability, i.e. what other needle shapes and emulsion tube sizes can be sourced. Once all of these variables are considered, the path that could unfortunately reveal itself might be not opening up the airbox quite this far. When I do this here, I open up the airbox until I know that I'm at the limit for what can be compensated for with the parts that I have access to.

Regards,

Derek

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Old 03-03-2013, 10:59 PM   #14157
Ladder106
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Quote:
Is this dam forward or rear facing?
The opening faces the rear of the bike. Sorry, forgot you were not DR750 oriented.

So, it would seem that pluggin it in is the next logical step.

The hole is in the air filter lid. On this bike the lid forms the left side of the airbox. Air enters through the center of the filter then out into the airbox before being taken into the carbs. I have other new air filters that are not opened any more than stock. That's why I felt pretty free with this one.
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Old 03-03-2013, 11:09 PM   #14158
motolab
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Quote:
Originally Posted by Ladder106 View Post
The opening faces the rear of the bike.
It's likely that the dam produces a vacuum inside the airbox at speed, meaning that the mixture at the same combination of throttle position and rpm would be different at a different road speed, which is clearly undesirable. It would be interesting to remove the dam and install larger main jets until the problem goes away. If the mixture is then too rich in the leanest spots at WOT on the dyno, that would demonstrate that the opening must be located in relatively still air.

Regards,

Derek
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Old 03-03-2013, 11:18 PM   #14159
Ladder106
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Quote:
It's likely that the dam produces a vacuum inside the airbox at speed
I was afraid you'd say something like that.

I've been thinking about redesigning the air box.

I'm planning to seal up the left side of the box, use a cleanable foam filter that operates in the normal (dirty air on the outside clean air on the inside) way.

Then opening a hole on the top of the box under the seat. Probably the best place for relatively still air. I have 15mm between the bottom of the seat and the top of the airbox
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Old 03-03-2013, 11:22 PM   #14160
Ladder106
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I was trying to somewhat duplicate what the Suzuki guys did. The standard air filter lid (left side of the airbox) looks like this (without the triangular hole in the front)



The black airdam is connected to a short "snorkel that protrudes about 30 mm into the airfilter area.
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