Joined Nov 2001
17K Posts | 774+
Ely, England
i took the carb into the engineer's and he has bored it to 41mm as he did with scoots. i had a blanking plate made for the end of the TPS shaft and most importantly i had a belmouth fitted.
most of you will have heard of this through dale. i had the alloy belmouth machined (as opposed to bored) out to take the blue plastic 50mm belmouth from keihin. this had to have the bolting lugs lathed off and then it was press fitted and araldited in.
the flare on the belmouth was reduced from some 72mm or so down to 68mm by just filing the outer rim slightly. this was done to allow the belmouth to fit in the air filter.
the air filter in question is a cone shaped pipercross filter PK003F. this filter fits into the triangulated area behind the sock-above the cross brace and between the two down tubes of the mid frame.
the standard outer Diameter of the belmouth for the sock is 62/64mm and the entry to the air filter is 70mm, so i had a white plastic ring machined up that was very broad and this was pressed onto the alloy belmouth.
i haven't made any extra holes in the plastic belmouth for the air feed to the PAJ and MAJ. because these belmouths are from a bank of four for jap multis: they have left a little straight 'nick' out of each side which is all the air feed that these two jets will need.
when first assesed i realised the air filter would push against the shock absorber so i filed away a production hole on the carb above the belmouth and what with the broad shoulder of the plastic i can now get the filter right against the carb and just about away from the shock.
i may even get a narrower jubilee clip and slice part of the filter's shoulder off and move it even further forward. the filter comes off the carb and off the belmouth easily now though.
the filter is foam and has a metal cage inside to give it shape. this i've ovalled very slightly but alas the filter toiuches the back of the boot mount in the frame and also sits on the cross strut in the frame.
the carb must be tightened on first and then the filter is tightened at an angle afterwards with the filter having to angle down slightly. so the top edge of the plastic ring on the belmouth can just be seen.
i've used the filter cleaning kit and oiler coded P/CC9005 and P/CC8999 and with the filter PK003F they can all be ordered in the UK from demon tweeks on 01978 663027, they're at wrexham in north wales. filter £34, cleaner and oiler were £20.
the blue belmouth i got from allins performance on 01949 836733, they are at bingham in notts. that was £13-all prices inclusive.
i've removed the original filter from the top of the housing and until i'm sure that this is working and WORTHWHILE i will leave it there touching the filter.
so far, when jet washing, i have rolled a plastic sheet up over and around the filter and it has been such a 'snug' fit that it was bone dry after a wash. there is less crap in the carb now than with the original set up!!! as the old set up required a shorter carb than the dell orto with a subsequent misfitting 'sock' and the grim that was within.
cleaning appears to be a pain because i need to wash without crushing the filter which isn't going to be easy.
PERFORMANCE
the carb is stronger at 1/4 throttle and switchback esses, this is the first time in second gear that the bike has lifted and the wheel not being where i wanted it. it's too early to say what the midrange and top are like but i do know that the 41mm bit of the equation only helped to top out in 6th gear.
so the bottom end performance boost is from the belmouth mod. next week i race with lots of open straights so we'll see!
the increase so far is 'small' but i'm not too sure where the bottleneck in the system is at present? i have some larger headers to try from 'simon' so it maybe they that help because they are the most needed.
regards
Taffy
most of you will have heard of this through dale. i had the alloy belmouth machined (as opposed to bored) out to take the blue plastic 50mm belmouth from keihin. this had to have the bolting lugs lathed off and then it was press fitted and araldited in.
the flare on the belmouth was reduced from some 72mm or so down to 68mm by just filing the outer rim slightly. this was done to allow the belmouth to fit in the air filter.
the air filter in question is a cone shaped pipercross filter PK003F. this filter fits into the triangulated area behind the sock-above the cross brace and between the two down tubes of the mid frame.
the standard outer Diameter of the belmouth for the sock is 62/64mm and the entry to the air filter is 70mm, so i had a white plastic ring machined up that was very broad and this was pressed onto the alloy belmouth.
i haven't made any extra holes in the plastic belmouth for the air feed to the PAJ and MAJ. because these belmouths are from a bank of four for jap multis: they have left a little straight 'nick' out of each side which is all the air feed that these two jets will need.
when first assesed i realised the air filter would push against the shock absorber so i filed away a production hole on the carb above the belmouth and what with the broad shoulder of the plastic i can now get the filter right against the carb and just about away from the shock.
i may even get a narrower jubilee clip and slice part of the filter's shoulder off and move it even further forward. the filter comes off the carb and off the belmouth easily now though.
the filter is foam and has a metal cage inside to give it shape. this i've ovalled very slightly but alas the filter toiuches the back of the boot mount in the frame and also sits on the cross strut in the frame.
the carb must be tightened on first and then the filter is tightened at an angle afterwards with the filter having to angle down slightly. so the top edge of the plastic ring on the belmouth can just be seen.
i've used the filter cleaning kit and oiler coded P/CC9005 and P/CC8999 and with the filter PK003F they can all be ordered in the UK from demon tweeks on 01978 663027, they're at wrexham in north wales. filter £34, cleaner and oiler were £20.
the blue belmouth i got from allins performance on 01949 836733, they are at bingham in notts. that was £13-all prices inclusive.
i've removed the original filter from the top of the housing and until i'm sure that this is working and WORTHWHILE i will leave it there touching the filter.
so far, when jet washing, i have rolled a plastic sheet up over and around the filter and it has been such a 'snug' fit that it was bone dry after a wash. there is less crap in the carb now than with the original set up!!! as the old set up required a shorter carb than the dell orto with a subsequent misfitting 'sock' and the grim that was within.
cleaning appears to be a pain because i need to wash without crushing the filter which isn't going to be easy.
PERFORMANCE
the carb is stronger at 1/4 throttle and switchback esses, this is the first time in second gear that the bike has lifted and the wheel not being where i wanted it. it's too early to say what the midrange and top are like but i do know that the 41mm bit of the equation only helped to top out in 6th gear.
so the bottom end performance boost is from the belmouth mod. next week i race with lots of open straights so we'll see!
the increase so far is 'small' but i'm not too sure where the bottleneck in the system is at present? i have some larger headers to try from 'simon' so it maybe they that help because they are the most needed.
regards
Taffy
