strugglinon Posted March 3, 2017 Report Share Posted March 3, 2017 So I've got myself another project bike. '93 JTR160 with a 250 motor in it as the previous owner couldn't find a 160 piston. it starts 2nd kick no problems, runs off choke happily. After 5-10 mins or so it's revs begin to pick as if the dry side main seal is passing air. let it cool down and it's back to normal. ill do a vacuum test on it this week, but could it be a stator problem? any suggestions? graeme Quote Link to comment Share on other sites More sharing options...
strugglinon Posted March 3, 2017 Author Report Share Posted March 3, 2017 I meant '94 not '93. took it as a '94from the frame number? "1694" (160cc 1994)? do you know the year from the frame number? regardless of that, any ideas on the running issues? Quote Link to comment Share on other sites More sharing options...
strugglinon Posted March 3, 2017 Author Report Share Posted March 3, 2017 Thanks for the clarification. It rides really nicely. Just got sort out this problem, then I can concentrate on tidying it up a bit. Quote Link to comment Share on other sites More sharing options...
mrturtle Posted March 4, 2017 Report Share Posted March 4, 2017 Have you cleaned the carb and jets? It could be dirt blocking the pilot jet then settling back down into the float bowl when the engine is stopped. Quote Link to comment Share on other sites More sharing options...
strugglinon Posted March 4, 2017 Author Report Share Posted March 4, 2017 I'll pull it out and get it through the ultrasonic cleaner too. I just need to go through the bike completely. It will make a nice bike I reckon. Quote Link to comment Share on other sites More sharing options...
strugglinon Posted March 9, 2017 Author Report Share Posted March 9, 2017 Ok, I've put a new main seal in on the dry side. carb has been cleaned in the ultrasonic bath. can anyone tell me what size the pilot jet should be? the motor is behaving the same way. Revs begin to rise steadily then level off. A bit of choke settles it down, so it's still running lean. hmmmmm? Quote Link to comment Share on other sites More sharing options...
uksg85 Posted March 13, 2017 Report Share Posted March 13, 2017 Sounds like it needs some new rim decals or maybe anodised bar ends. All the best, Scott 1 Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted March 21, 2017 Report Share Posted March 21, 2017 It sounds like the engine is getting a lean mixture. Check to see if the fuel tank is venting correctly. A simple test is when it starts to rev up is to loosen the fuel cap. If it slows down, the vent is plugged. Quote Link to comment Share on other sites More sharing options...
strugglinon Posted March 26, 2017 Author Report Share Posted March 26, 2017 Well Ive managed to sort it all out. the gasket between the reed block and intake manifold was letting air in. Took me ages to find because I took the reed block off to seal the motor for a vacuum test. the gasket in question was a piece of gasket paper, cut out to fit. Replaced it and happy days. i like this old bike. It rides really nicely. Quote Link to comment Share on other sites More sharing options...
andybon Posted May 14, 2017 Report Share Posted May 14, 2017 I have just got hold of a similar bike, doesn't look as clean as yours though, in need of new plastics for it which seem impossible to find! Quote Link to comment Share on other sites More sharing options...
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