jimmer Posted July 22, 2011 Report Share Posted July 22, 2011 Hi there, i am new to the sport and this forum, and need a bit of help: i have a 1975 ty175, and rode it the other day for the first time for a couple of hours. The engine didn't like to idle and kept stalling, which made steep descents difficult. I was low on fuel, and the problem doesn't seem to occur when the engine is cooler and just off choke. Is it just lack of 'pressure' from low fuel or something else? Also another elementary question - does the 'search' thing work on this? it keeps telling me i am using banned words (and i am not...i don't think!) cheers for your help Quote Link to comment Share on other sites More sharing options...
keychange Posted July 22, 2011 Report Share Posted July 22, 2011 (edited) Also another elementary question - does the 'search' thing work on this? it keeps telling me i am using banned words (and i am not...i don't think!) You are not allowed to say f@&%ken in relation to a Yamaha or Honda but it is allowable for Montesa or Bultaco. Words like ars*^$le or di$%*ead are only acceptable when referring to the forum moderator or a monoshock rider - I hope this helps with the post problem. As for bike problem it is unlikely to be a fuel pressure problem as long as your tank is properly ventilated (usually a fuel line heading to the steering column) check to ensure it is not blocked. But sounds more like a carbie issue. Start by make sure the air filter is clean ( I mean new ) and then ensure everything in the carbie is clean ie: all jets are clear etc. Then check that the float level is correct and that the float needle seat valve is working properly (otherwise it floods and outcome is as described. Then replace and ensure you are using the correct spark plug and ensure that you are running correct fuel/oil mix - contrary to common opinion more oil can do more damage than too little oil. Having done all that report back Edited July 22, 2011 by keychange Quote Link to comment Share on other sites More sharing options...
dadof2 Posted July 22, 2011 Report Share Posted July 22, 2011 "contrary to common opinion more oil can do more damage than too little oil" That statement just is not true - too little oil WILL cause rapid wear and probably wreck the whole engine. The most likely worst thing too much oil will do is foul the plug or make the bike hard to start. Cheers Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted July 22, 2011 Report Share Posted July 22, 2011 (edited) Strip & clean the carb, surrounding the main jet is an O ring that seals into the float chamber, it will become obvious which one I mean when you dismantle the carb. Replace this O ring with one that is a good fit into the ring groove and the float chamber & the problem should be resolved. O rings can be purchased from enginers merchants or agricultural suppliers. The TY 175 is a great little bike, ours runs well on a 35 to 1 semi-synthetic petrol oil mix. Edited July 22, 2011 by TrialsRfun Quote Link to comment Share on other sites More sharing options...
jimmer Posted July 22, 2011 Author Report Share Posted July 22, 2011 All advice gratefully received, my success rates with fixing carbs is poor, but this may be a chance to put it right! I was about to ask about furl mix too - it had been run on 30:1, and i was recommended 40:1, so 35:1 should be about right. I remember smelling the Castrol R veggie mix as a kid - is this an option still? Quote Link to comment Share on other sites More sharing options...
jimmer Posted July 22, 2011 Author Report Share Posted July 22, 2011 Sorry meant to ask - do i need new gaskets when refitting carb? if so where is the best place to buy such an item? Quote Link to comment Share on other sites More sharing options...
goudrons Posted July 22, 2011 Report Share Posted July 22, 2011 Sorry meant to ask - do i need new gaskets when refitting carb? if so where is the best place to buy such an item? Try John Cane at http://www.tytrials.co.uk/ for spares. Sounds like it's running lean if it's idling poorly when hot. Does it pop and bang and fail to return to a smooth idle as well? http://www.trialsport.com.au/TY175/ Make sure your oil/petrol ratio is correct, a under mix will allow the engine to over heat. Float high should be 21mm. The choke lever, where it pulls out the body, are known to draw air, particularly if the lever is bent after a drop. Are the crankseals good, could they be leaking? Remember the mixture screw is actually a air screw, screwing it in riches, out leans. I always found the stock pilot of 25 a bit lean for trials work, may be worth trying a 30 if all else fails. Quote Link to comment Share on other sites More sharing options...
jimmer Posted July 22, 2011 Author Report Share Posted July 22, 2011 Does a 30 richen the mix or something, and how does that help with trials demands - just in terms of low revs? Quote Link to comment Share on other sites More sharing options...
bashplate Posted July 23, 2011 Report Share Posted July 23, 2011 All advice gratefully received, my success rates with fixing carbs is poor, but this may be a chance to put it right! I was about to ask about furl mix too - it had been run on 30:1, and i was recommended 40:1, so 35:1 should be about right. I remember smelling the Castrol R veggie mix as a kid - is this an option still? don't use castrol R, it goes 'off' very quickly and gums up the carbie. you be much better using one of the modern synthetic oils. Quote Link to comment Share on other sites More sharing options...
jimmer Posted July 23, 2011 Author Report Share Posted July 23, 2011 Does it pop and bang and fail to return to a smooth idle as well? No it doesn't, just slowly loses revs and stalls Quote Link to comment Share on other sites More sharing options...
goudrons Posted July 23, 2011 Report Share Posted July 23, 2011 Does a 30 richen the mix or something, and how does that help with trials demands - just in terms of low revs? To an extent, yes a 30 pilot will richen the fuel/air mix as it's a bigger one than the 25 that came as standard. By the sounds of what you write, your engine is heating up and getting lean, struggling to idle. There are a number of factors that will cause this, An air leak, air being drawn in somewhere, like a split manifold, leaking reed cage gasket, the choke lever shaft or even a leak in a crank seal (although this will also allow mixture to escape depending on what stroke the piston is on). This adds extra air to the mix, leaning it up Float level set too high, this will starve the engine of fuel and lean the mixture off. Same goes for a blocked fuel tap or tank vent in the fuel cap. A lean fuel/oil mix will cause the engine to get hot and give you the same effects as a lean fuel/air mixture. Incorrect ignition, this can set the spark off at the wrong time causing the same effects as a lean mixture. The air cooled engine can get hot, particularly in trials, where it may not get the same passing air across the fins as it would on the open road. An exhaust change can effect the mixture, blocked or a new one that handles the gases better? So before you go off and try and "buy" your way out of your problem, you need to be certain everything else is right or you'll be forever chasing your tail! Fuel/oil mixture Ignition correct No air leaks in the system, no block in the tank/tap. Float high correct It is the right carb. Are the carb parts correct- right slide, right needle, needle is right high, right jets (to start with) The carb and filter are clean If these are right, then you're looking at a naturally occurring issue with the engine, like it's getting hot 'cos it's not getting enough passing air, or the exhaust is now letting more gases out quicker, this is the time to think about a bigger jet. Quote Link to comment Share on other sites More sharing options...
keychange Posted July 24, 2011 Report Share Posted July 24, 2011 "contrary to common opinion more oil can do more damage than too little oil" That statement just is not true - too little oil WILL cause rapid wear and probably wreck the whole engine. The most likely worst thing too much oil will do is foul the plug or make the bike hard to start. Cheers Most people know not to forget to add oil and so while lack of oil is catastrophic it is not common among riders with half a brain. A rich oil mix means by definition a leaner fuel (petrol/air) mix and leads to a hotter running engine - I agree not as instantly catastrophic but none the less can be serious simply because the issue is not recognised ie: my engine is running too hot - I better add more oil or a cooler plug Neither of which addresses the air/fuel mix issue. - Not a problem when riding quietly but serious damage can occur under regular hard load.This is a common issue for chain saw users who use their 25:1 lawn mower mix in their 50:1 saw - it overheats very quickly. Quote Link to comment Share on other sites More sharing options...
jimmer Posted July 25, 2011 Author Report Share Posted July 25, 2011 Thanks for taking the time to provide mw with some details on carbs etc. I was reading the Haynes manual last night on carb settings and see that a low idle - to the pint where is stalls is even preferred by some trials riders whiles others like it opposite to that, so thats got me wondering whether its just the set up! Just to clarify - i've been advised on running it at 30:1 40:1 even 50:1 on synthetic oil - whats the general consensus? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 25, 2011 Report Share Posted July 25, 2011 sorry this might be a bit obvious but have you tried adjusting the idle speed yet? There should be a thumbscrew on the side of the body that adjusts the height of the throttle slide to adjust the idle speed with Quote Link to comment Share on other sites More sharing options...
jimmer Posted July 27, 2011 Author Report Share Posted July 27, 2011 sorry this might be a bit obvious but have you tried adjusting the idle speed yet? There should be a thumbscrew on the side of the body that adjusts the height of the throttle slide to adjust the idle speed with Yep...that did the trick, but now have run into another problem...see new thread if you can help!! Quote Link to comment Share on other sites More sharing options...
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