frenchie Posted August 16, 2008 Report Share Posted August 16, 2008 My Majesty is the 320 version and ever since I bought it I have always felt it could and should run better, sweeter, nicer than it does. I have been down the airbox modification route, I ve changed the carb for a new Mikuni and re jetted it, it runs on a lean petrol oil mix . In fact it recently came back to the uk for a very well respected friend to have a look at it and although its improved its still not right. Now, bearing in mind you can write on a stamp what I know about engines, it still seems weak to me and does nt have a crisp engine note or really likes to rev out. My question, is it due to the fact of the engine size and would a better bet be to reduce it back to a 250 with the appropriate jetting etc etc as the 320 is just to big to get to run riight or am I and my band of helpers missing something. Getting to the stage where it may be shown the door and a Fantic in the garage instead. The spec is pilot jet 35 main jet 150 , electronic ignition, full wes exhaust ( year old ) Any help would be really apprciated. Thanks very much. Frenchie Quote Link to comment Share on other sites More sharing options...
tony283 Posted August 16, 2008 Report Share Posted August 16, 2008 (edited) Frenchie, You say you have a Mikuni and when I rebuilt a Majesty motor using the whole "kit and koboodle" I put a new Mikuni VM26 on and rather like yours it would not run smoothly. After asking the questions with Craig the correct jetting for the Mikuni is 35 pilot and 290 Main. Yes, thats right TWO NINETY it is not a typo. After fitting that size the performance was spot on with no other changes required. As a general rule with the Mikuni, which I also use on my 1960 Royal Enfield Bullet, for 2 stroke you need to INCREASE main jet size with increasing cc's and with 4 strokes DECREASE. Tony Edited August 16, 2008 by tony283 Quote Link to comment Share on other sites More sharing options...
martinm Posted August 16, 2008 Report Share Posted August 16, 2008 My Majesty is the 320 version and ever since I bought it I have always felt it could and should run better, sweeter, nicer than it does. I have been down the airbox modification route, I ve changed the carb for a new Mikuni and re jetted it, it runs on a lean petrol oil mix . What petrol/oil mix are you running Frenchie ??? You should be on 50:1 fully synthetic. If you are running a higher fuel/oil ratio (eg 80 or 100:1) you are actually running richer not leaner.....your bike is getting more fuel than air. Stick it back to 50:1 and start looking at the pilot jet circuit if the bike is sluggish picking up. Martin Quote Link to comment Share on other sites More sharing options...
mollygreen Posted August 16, 2008 Report Share Posted August 16, 2008 Stick it back to 50:1 and start looking at the pilot jet circuit if the bike is sluggish picking up. Martin I run 100:1 in my TY250 T/S. This with an airbox mod has created a need to raise the needle to make it run richer than the standard setting. It now runs absolutely lovely and a lot sweeter than the 270 Beta Rev 3 I had new in 2001. (Which I also ran on 100:1) You don't need to run any 2 stroke on 50:1 these days, all you'll end up doing is choking everyone you ride with and prematurely clogging up the exhaust which will cause you performance problems in the future. Quote Link to comment Share on other sites More sharing options...
frenchie Posted August 16, 2008 Author Report Share Posted August 16, 2008 Hi Thanks for the responses, I run it with a mixture of 2/2.5 pct which in imperial is around 50/1 60/01 I think... using a good synthetic oil. The pick is not slow to pick up in fact its alright low down its only when I have to go up the rev range it seems to feel and sound restricted. The problem seems in my humble opinion the carb set up... and trying to get the difinitive jets. Now I know with all bikes they can be slightly different with exhausts, ignition etc but my main jet of 150 and Tony mentioning 290 seem to be a country mile apart. I will try and get a selection of jets around the 290 mark and see how we go from there. Again any other suggestions jet size or otherwise would be welcome Thanks for your help so far. Bon Soir frenchie Quote Link to comment Share on other sites More sharing options...
tony283 Posted August 16, 2008 Report Share Posted August 16, 2008 Frenchie, As I said 290 was the "benchmark" for starting, pilot jet stays the same. In order to evaluate if the jetting is correct take the cleaner off and then with the dead engine mark a datum on your twistgrip body and the twistgrip rubber with an easy to see color like white. As you open the throttle and can see the slide move from idle mark the TG at 1/4 then 1/2, 3/4 and full. Remember where the problem, if any, occurs then take action. As an "idiots guide" closed to 1/4 = pilot and airscrew. 1/4 to 3/4= slide + needle. WFO= main Good luck, when you get it right you WILL be thrilled! Tony Quote Link to comment Share on other sites More sharing options...
mattylad Posted August 19, 2008 Report Share Posted August 19, 2008 Can I ask what airbox mod you are using? Quote Link to comment Share on other sites More sharing options...
frenchie Posted August 19, 2008 Author Report Share Posted August 19, 2008 I.ll let someone more technical minded than me to answer that, but mine involved more airholes/slots and a different air filter. Quote Link to comment Share on other sites More sharing options...
woody Posted August 19, 2008 Report Share Posted August 19, 2008 Or you can rip out the centre tube to open the airbox up and fit a top loading filter like the TY Mono. Not done that myself as I've an alloy airbox on mine but I've seen it done. Supposed to increase airflow. When I first bought mine it had the standard airbox, in very bad shape, hence the alloy fabricated one, and it was drilled through the front and both sides with holes, using the standard filter. No idea what difference the holes being there made, if any to be honest, but that bike revved its nuts off so there was no problem with airflow through the standard filter. Quote Link to comment Share on other sites More sharing options...
pitley Posted August 20, 2008 Report Share Posted August 20, 2008 My Majesty is the 320 version and ever since I bought it I have always felt it could and should run better, sweeter, nicer than it does. I have been down the airbox modification route, I ve changed the carb for a new Mikuni and re jetted it, it runs on a lean petrol oil mix .In fact it recently came back to the uk for a very well respected friend to have a look at it and although its improved its still not right. Now, bearing in mind you can write on a stamp what I know about engines, it still seems weak to me and does nt have a crisp engine note or really likes to rev out. My question, is it due to the fact of the engine size and would a better bet be to reduce it back to a 250 with the appropriate jetting etc etc as the 320 is just to big to get to run riight or am I and my band of helpers missing something. Getting to the stage where it may be shown the door and a Fantic in the garage instead. The spec is pilot jet 35 main jet 150 , electronic ignition, full wes exhaust ( year old ) Any help would be really apprciated. Thanks very much. Frenchie If your going back to 250 frenchie, keep me in mind for the 320 parts. Cheers Quote Link to comment Share on other sites More sharing options...
frenchie Posted August 22, 2008 Author Report Share Posted August 22, 2008 I ve decided to keep it a 320, mainly because changing it to a 250 might just open up another can of worms........ and also in the hope that the coming seasons trials ( In France ) may get away from the tricky, tight, nagery sections and might include some big hills, mud so I can take advantage of the bigger engine. Thanks for the replys and I am on the case and hopefully I will sort it. Frenchie Quote Link to comment Share on other sites More sharing options...
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