What did you do with your Trials Bike today?

[Shercoman]

Originally Posted by Twin-shocker

Its really a very good idea to fit a mudflap to any air-cooled bike thats going to get used in muddy conditions, as air-cooled cylinders really dont work very well at all when they are clogged with mud!

This is very good advice.
Back in the ATV 3 wheeler days,I showed up at a mud race with a piece of sheet metal clamped to the frame in front of the cylinder on my ATC 250R.
Got a lot of ribbing before the race.
Mine was the only 250R that finished the race.
Gotta keep that mud out of the fins!!

[JeffS77]

it had somemud in the fins but wasnt packed..nothing worse then i have done to any bikes in the past.

mud flap..hell I got a trials front fender with the molded in flap on the back..not sure how much more protection i can get out of a fender.

[Twin-shocker]

Originally Posted by JeffS77

it had somemud in the fins but wasnt packed..nothing worse then i have done to any bikes in the past.

mud flap..hell I got a trials front fender with the molded in flap on the back..not sure how much more protection i can get out of a fender.

If the bike didnt overheat due to clogged fins, then it seems like you might either have worn main bearings, or possibly an issue with the type/amount of 2T oil used in the fuel.

[JeffS77]

just running repsol standard 2T injector oil...i have a suspension it had too hot of a plug..I always run NGK B7's in it but swapped out a Champion in it that i was told was the same plug when cross referenced..but i think somebody was lying...gonna cross reference tonight my self....that parts counter boy better hide when i get there

I thought I heard it pinging but my dad was riding it and he is hard of hearing. when I asked him he said it was running fine. I am not sure he heard the ping


the bike was getting plenty of oil the reeds and crank where nice and oily.

[brewtus]

Originally Posted by JeffS77

.i have a suspension it had too hot of a plug..

Gotta love autocorrect....

Originally Posted by JeffS77

just running repsol standard 2T injector oil..I thought I heard it pinging but my dad was riding it and he is hard of hearing.

Not that it really means anything, but a number of years ago I tried the Repsol pre-mix oil in my TXT270. It started making some not-so-good sounds out of the engine soon after the change. I got nervous and changed back to the Motul Off-Road pre-mix I had been running previously. Not a month afterward, the Repsol rep came into the Honda dealership where I worked at the time to help promote Repsol products in the US (this was around summer of 2006). He was very...enthusiastic about Repsol oil for MX and Roadracing, but when I asked him about using it for Trials use (low mixture ratio), he kinda screwed up his face and stumbled/gestured (remember he was a Repsol rep-from Spain. English was NOT his first language) "No no, no Trials good, no. Good for Roadracing!!" Well, that kinda convinced me right there. Motul Off-Road it's been ever since in my TY's, along with the 314 and 315 Montesas I own. The Repsol oil is now the pre-mix of choice for my Daytona Special Yamaha.

I'm also assuming since you said you were running the injector oil that you still have the injector system installed on your TY. This is merely my humble, but I would remove that and run the TY with pre-mix. I've never been a big fan of the injector pump system (too vague and susceptible to environmental influences for my trust), and have removed it from every OE injector-equipped bike I own, running pre-mix instead. This includes all my TY's, the aforementioned RD400F Daytona, and my TG50 Gyro S Honda scooter. I replaced lots of top-ends on injector-equipped bikes back in my previous career as a motorcycle tech, and substantially less on pre-mix bikes. Just sayin'.

[JeffS77]

Originally Posted by brewtus

I'm also assuming since you said you were running the injector oil that you still have the injector system installed on your TY. This is merely my humble, but I would remove that and run the TY with pre-mix. I've never been a big fan of the injector pump system (too vague and susceptible to environmental influences for my trust), and have removed it from every OE injector-equipped bike I own, running pre-mix instead. This includes all my TY's, the aforementioned RD400F Daytona, and my TG50 Gyro S Honda scooter. I replaced lots of top-ends on injector-equipped bikes back in my previous career as a motorcycle tech, and substantially less on pre-mix bikes. Just sayin'.

and then all my vintage Yamaha buddies say DO NOT disconnect the oil injection and some of them do put tons of miles on their bikes...tomato - tomato

I run the 2T standard injector oil



and I ran this stuff in a '68 Kawi Bushwacker I totally abused and never had a problem with it.

Just checked a pulg and it is a Champion 8902..is anything it is a tad cold like a NGK B9ES


oh and you got a GYRO ?? cool a buddy of mine just picked up a Honda Express SR...another odd bike...Honda made some cool stuff in the 80's

[NMTrailboss]

Originally Posted by JeffS77

...Honda made some cool stuff in the 80's

Yup.... I miss the old Honda.

[Twin-shocker]

Not a great idea to use autolube systems on any off road machine.............I think the seizure of the TY175 presents a very good reason to change to pre-mix, using a proper pre-mix oil!

Autolube type 2T oils contain up to 20% kerosene to make them thin enough for use in autolube systems, which can mean in real world terms that a motor may well be running on something like 150:1 fuel-oil ratio in some circumstances.

An awful lot of people use unsuitable (autolube type) oils in pre-mix applications, and this means in effect 20% less oil, and far higher chance of corrosion damage occurring when bikes are not being used, as the very thin autolube oils are simply not as good as proper pre-mix products at preventing rust forming on internal engine parts.

Here in the UK there are many cases of main bearing failure on machines with very low hours, and the main reason for these failures is use of autolube type oils and our very damp weather, which leads to corrosion on bearing tracks during storage, and then directly to early failure of the bearings themselves!

If you are selecting a 2T oil for off road use, make sure it has "Pre-Mix use Only" clearly marked on the packaging. If it doesnt than it will be a dual purpose product, which manufacturers suggest can be use in both pre-mix and autolube applications, but this claim is far from accurate when related to 2T trials machines, which run best on very lean mix ratios, which should never be used if you have autolube type oil.

[UngaWunga]

Auto-lube pumps are great for road going two strokes. Stupid to run premix on the street. But racing and offroad is another matter. Always premixed when roadracing. I'd do the same with offroad.

[brewtus]

Originally Posted by NMTrailboss

Yup.... I miss the old Honda.

Same here.


As I said about the autolubers - just my humble, and my experiences. That's all.

[JeffS77]

ok after having the bike examined by some vintage Yamaha experts the following has been concluded,

The bike was running very lean..even with its fat jetting and a semi cold plug..suspected flywheel side seal failure
this resulted in an overheating condition that then caused the lower ring to catch the exhaust port and cause the serious damage.

Oil pump is functioning fine and the reeds and crank had plenty of oil. pump was also tested to be working fine...failure was caused by a very lean fuel condition.

after working the cylinder a little and honing and test fitting with the .25mm over bore piston all looks good and it should be back up and running in no time as soon as the new small end bearing,pin and base gasket come in

this weekend I will flush the lower end with some mineral spirits to make sure no crud is left floating around down there and hopefully have her all buttoned up next weekend.

[brewtus]

Nice!

Pics, pics....

[Twin-shocker]

Originally Posted by JeffS77

ok after having the bike examined by some vintage Yamaha experts the following has been concluded,

The bike was running very lean..even with its fat jetting and a semi cold plug..suspected flywheel side seal failure
this resulted in an overheating condition that then caused the lower ring to catch the exhaust port and cause the serious damage.

Oil pump is functioning fine and the reeds and crank had plenty of oil. pump was also tested to be working fine...failure was caused by a very lean fuel condition.

after working the cylinder a little and honing and test fitting with the .25mm over bore piston all looks good and it should be back up and running in no time as soon as the new small end bearing,pin and base gasket come in

this weekend I will flush the lower end with some mineral spirits to make sure no crud is left floating around down there and hopefully have her all buttoned up next weekend.

"If the bike didnt overheat due to clogged fins, then it seems like you might either have worn main bearings, or possibly an issue with the type/amount of 2T oil used in the fuel."

Contrary to the view of your vintage Yamaha experts crank seals very rarely fail, and leakage here will in almost all cases be due to worn main bearings.

The proper way to work out if you have an air leak is to pressure test the bottom end of your motor, which will quickly indicate any leaks, and allow you get any faults repaired.

[JeffS77]

Originally Posted by Twin-shocker

"If the bike didnt overheat due to clogged fins, then it seems like you might either have worn main bearings, or possibly an issue with the type/amount of 2T oil used in the fuel."

Contrary to the view of your vintage Yamaha experts crank seals very rarely fail, and leakage here will in almost all cases be due to worn main bearings.

The proper way to work out if you have an air leak is to pressure test the bottom end of your motor, which will quickly indicate any leaks, and allow you get any faults repaired.

I wouldn't venture to say very rairly fail... This bike is almost 40 years old and spent most it's life stored in very extreme weather conditions and sat for loong periods of time... I would say very likely for the seals to fail....we pulled the side covers off and have no play in the crank... I think old age and inproper storage ofthe bike is too blame. I have seen many a two stroke stored for long periods of time wind up needing crank seals and have totaly fine bearings.

Oiling on this bike was not an issue.


I will probably start another thread as to not totally hijack this one

[Twin-shocker]

Seals will go hard if stored for years certainly...........a good idea to replace them with viton rubber ones if thats the case...............