nitjay - hrc Posted April 13, 2007 Report Share Posted April 13, 2007 (edited) Hi, i posted something about this on the backend of someone elses post, (sorry for attempted hijack) I left it there for a while but now decided to try and start a new thread. My SY250 is great for (southern) clubtrials, the power delivery is perfect for off camber turns and getting traction. However recently i have been riding a much larger piece of land which contains rocks and giant climbs. However im a bit scared of attempting them on the Scorpa, i know im capable, however im worried i wont get it right as i cant get the bike to rev freely enough for me to gain traction at the bottom and carry me to the top (without a lot of strain anyway!). This means i have to use 4th which gets hairy whent the climbs steepen at the top. As my mate who got it up there said "it just decides it doesnt want you to rev it anymore thankyou" Im not sure if there is something wrong with it, the carb is clean as anything same with the airbox and filter (as always) however if i ride the bike and rev it quite a lot going up a climb or something, about 3/4 of the way up the rev band there is a cracking sound that is coming from right beneath me, it goes away if i let it rev some more. But i just wondered what this could be? I have got a slow throttle on there at the moment so im going to try the fast one to give it a little more snap. Any other ideas? I thought i read something about changing the jets but maybe i imagined that. Thanks Edited April 13, 2007 by Nitjay - HRC Quote Link to comment Share on other sites More sharing options...
fozza321 Posted April 13, 2007 Report Share Posted April 13, 2007 what about the petrol, maybe try putting it on reserve goin up hills?? just a thought Quote Link to comment Share on other sites More sharing options...
jumbostu Posted April 13, 2007 Report Share Posted April 13, 2007 What main jet are you running? and is your air filter really clean or contaminated with too much filter oil?? Check out the Scorpa Hell Team site for altering your timing and other tips. Regards jumbostu Quote Link to comment Share on other sites More sharing options...
dgshannon Posted April 13, 2007 Report Share Posted April 13, 2007 I have got a slow throttle on there at the moment so im going to try the fast one to give it a little more snap. A fast throttle is not going to do anything for the problem you are describing. The Scorpa has an adjuster plate that will let you change you timing, very easy. For whatever reason, different areas get bikes with different timing settings, and different flywheel weights. You more than likely have a heavy flywheel, and retarded timing. Try advancing your timing a bit, and see if the problem gets better. Quote Link to comment Share on other sites More sharing options...
baldilocks Posted April 13, 2007 Report Share Posted April 13, 2007 Hi I had a 2006 model which revved to the moon. It was a racing version with lightened flywheel and Ign timing fully advanced mind but i would just advance the timing first. Couple of other points, dont tape up around the air intake, leave it standard in case your restricting air flow. As an experiment see how high it will rev with the mudguard off. The curious thing about my scorpa was if you tried to clean it out before entering a section it wouldnt rev out but under load it did rev, so perhaps they have some kind of rev limiter . Are you slipping the cluch heavily when the problem occurs ? Quote Link to comment Share on other sites More sharing options...
gasgasian Posted April 13, 2007 Report Share Posted April 13, 2007 Take a look @ middle box, very often cracked and leaking on this model, could be the noise you r hearing as well, a cracking popping sound,this will affect back pressure to engine resulting in poor carburation. Regards, Ian. Quote Link to comment Share on other sites More sharing options...
nitjay - hrc Posted April 14, 2007 Author Report Share Posted April 14, 2007 (edited) Thanks for all your tips! I have just repaired the middle box so that seems ok. How do i advance the ignition timing, is it difficult? I cant get the Hell Team link to work. Basically if you dont mind could i have more detailed information about this. Ive ridden my bike with the airfilter wrong and i really felt that, it seems to breathe ok, so that seems good. I cant remember which main jet iam using, however i believe its the standard one. Thanks lads keep them coming please! Also, after i ride the seal between the cylinder and the exhasut becomes quite gunky - could this cause problems Edited April 14, 2007 by Nitjay - HRC Quote Link to comment Share on other sites More sharing options...
baldilocks Posted April 15, 2007 Report Share Posted April 15, 2007 (edited) Exhaust / cylinder joint could be a problem take it off and see if its blowing. If a scorpa is right it will rev so somthings wrong with it. To advance the timing you need to move the stator plate in the opposite direction to which the engine turns. Push the kickstart with your hand to check which way it turns. You can fully advance the timing. Edited April 15, 2007 by Baldilocks Quote Link to comment Share on other sites More sharing options...
arnoux Posted April 15, 2007 Report Share Posted April 15, 2007 Hey Nitjay Sorry about the broken links on my website (wwwthehellteam.com) - it's now fixed. Can you blokes please let me know if you find any broken stuff like that, so repairs can be carried out Pronto! The leak at the header will definitely affect bike performance, fix that straight away. Jet wise, standard is 145 and it tends to be a little conservative (gotta cover yourself against long sustained high rev trail type riders, or SSDT type situations). In most trial situations you will find a leaner main jet will really help the Yamaha 4gg motor rev much cleaner. Use your head when leaning out main jets, but 140 to 136ish should be OK. You will notice a big improvement. Oh, and they dont have a rev limiter. All the best Arnoux Quote Link to comment Share on other sites More sharing options...
nitjay - hrc Posted April 15, 2007 Author Report Share Posted April 15, 2007 (edited) Thanks thats great! I was actually going to email you to say the link was brokern but i thought it must have been my computer. What am i likely to need to fix the exhaust at the front? There is a Yam Motox dealer near me am i likely to be able to get the jet from them, or should i ring birketts? Thanks Edited April 15, 2007 by Nitjay - HRC Quote Link to comment Share on other sites More sharing options...
arnoux Posted April 15, 2007 Report Share Posted April 15, 2007 Well you'll have to pull it apart to make that decision! You made need to replace the gasket, or you may just need a squirt of high temp gasket sealant around the matching faces. You will need to remove a bit of the rear part of the exhaust to get the header pipe off. Also a cut down allen key for the left side bolt makes life a bit easier. Jet - Get that from Birk's. Support your Trials dealers! Do you see much trials stuff in your local Yamaha dealer? Also Birkett's may be able to advise what jet size for UK conditions is best. (We are a long way away after all!) Cheers Arnoux Quote Link to comment Share on other sites More sharing options...
nitjay - hrc Posted April 16, 2007 Author Report Share Posted April 16, 2007 Thanks for the info! Quote Link to comment Share on other sites More sharing options...
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