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old fart
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3,641 Posts
Discussion Starter #1,161
Fcuk, why do we bother with Carbs?? i have had them on, off, taken apart, re assembled and re adjusted a dozen times so far this weekend!!

started back at pilot screws 3/4 of a turn out (best idle) and Pilot air jet 2 full turns out. (factory supplied)

slowly over a few runs i turned the pilot air jet in by 1/8 turn each run.

each run seemed better, less hesitation and juddering.

have ended today with her at pilot screws at 1 turn out, and pilot air jets at 1- 1/4 turns.

almost sorted, but started to throw it down, so called it a day.

never thought that fitteng a different link pipe and end can would upset the fueling so much!! but it is

the only change that i have made to the induction/exhaust over winter.

i have done a web search and turned up a few articals on Yoshi MJN/TMR's doing the same thing on other bikes, seems they need to be teased to get them to transition cleanly, so looks like i have some more adjustments to do yet.

in other news, have now settled on the GSX map on my Ignitech, after input from other members of this/other forums.
 

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old fart
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3,641 Posts
Discussion Starter #1,162
its like trying to hold onto a wet eel, just when you think you have it, it slips away again FFS, yesterday afternoon was spent with carbs i one stage of disassembly or another.

had it almost sorted on the initial throttle settings, but wasn't happy with the hunting idle, so it was decision time, went for trying the MJN on a different clip, couldnt find anything i could understand in the Mikuni TMR handbook (Japanese only) and not got any mention of the Yoshi MJN at all in it!

from what i could find out on the web on other forums, the consensus was to do the opposit of normal carb needles and move the MJN DOWN to get a richer mixture, having thought about it, I didnt myself think that it was a correct solution, but i would give it a try anyway.

well with the clip moved up one slot (MJN lowered) the bike would die when given even a sniff of throttle!!! so back apart and clip moved down two slots (raise MJN)

this resulted with bike reving cleanly from initial throttle through and past 3k (area of problems)

got a feeling that i am now in the area of needing a bigger pilot fuel jet, as the air jet is only just screwed out 1/2 a turn.

At this point in the proceedings @JamesHambleton turned up to return my bike ramp, that he had been using, so spent the next couple of hours putting my bike back together slowly and talking Shit. always good to see you mate :)

will be taking her out again later for another shake down run,
 

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Super Moderator
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5,627 Posts
This is starting to sound like this one 4cc two stroke nitro engine I had in an RC plane way back when :D you could EITHER get it to run clean when hot and WOT but it was a pig to start, OR you could get it to idle but not rev when warmed up. Kinda hard to fly cause dropping the revs down past half you risked stalling mid flight.

Come to think of it I still have the frame... Wonder what it'd cost to get back up...
 
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old fart
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3,641 Posts
Discussion Starter #1,166
been away for most of the weekend, got back and played around a bit more, now 99% there, just very very slight lean stumble when on constant just open throttle, at low speed,

let her cool down, then did the pilot airs 1/8 turn close.

i am confident that that will work, test run tomorrow :)
 

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old fart
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3,641 Posts
Discussion Starter #1,167
went straight through her MOT this afternoon, knew it was sometime soon, but when i checked my old form it ran out yesterday!!!

got her booked for a fueling run on the Dyno for Wed afternoon.

also contacted Performance spares (yoshimura UK importers) to see what alternate MJN's are available.
 

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old fart
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3,641 Posts
Discussion Starter #1,168
did a few runs on Stu's dyno at*Dyno Centre Northallerton, was better fueling than i had thought, but we both think there is something else wrong, the stutter

at 4K wont move with jetting changes? so might be electrical in nature.

i have some mains on order, and will be getting some more runs when they arrive.



red run last of the day.


 

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old fart
Joined
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3,641 Posts
Discussion Starter #1,169
think i have now got to the bottom of the ignition stutter, i have removed the Ignitech ignition module and re fitted the stock B12 ECU, been out on bike, got her up to temp (+60 deg C)

opened her up slowly in top, did smooth roll on through to 80mph..................No stutter

rode her around at around 4K (60mph in top gear) for a bit trying to get her to play up, NOTHING

let temp rise through to 85 deg, still nice and smooth,

then did fast top gear roll on up to 110mph, still no stumble
rode her home still nice and smooth through all gears, looks like i will need to get the Ignitech sent back for a check out to find the problem!

fingers crossed it is sorted now and i can actually get out and ride her this summer, will contact Stu

for another Dyno session.
 

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old fart
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3,641 Posts
Discussion Starter #1,170
managed to get all of the 50 miles to work this morning without a stumble or protest from anything :rock:

Happy boy this morning, i is :thumbsup:
 

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old fart
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3,641 Posts
Discussion Starter #1,171
whilst playing around with the Yoshi TMR-MJN's jetting it struck*me that i had not seen any replacement or fitment kits for different MJN's?? and as my needles were marked as "C" fitment, there must at least be an A and B fitment too?*

i did a web search but came up empty handed, TMR handbook had no listing or spares for the Yoshi parts, even Webike had nothing on their site.

looked like the only way to get the MJN's is to get a set of carbs built for specific bike by Yoshi Japan to order!!*

So i gave the Yoshi UK importers Performance Spares a phone call, they checked out their catalogs and listings but could throw no light on the availability of replacement MJN's

they said that they would send off an E-mail to Yoshi Japan to see what they had to say on the subject. but agreed with me that if there is a C there must be other sizes.

Got a phone call from them this morning, Yoshi Japan had sent a reply and listed MJN fitments from A to F with part No's and recommended bike fitments.

So the info is out there! its not what you ask, but who you ask that counts*​​​​​​​
 

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old fart
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3,641 Posts
Discussion Starter #1,175
well what a difference a properly sorted coil connection make, not perfect, but will do me for now.

131bhp and 80 torques, she also runs nice on the road, should be good for some more with the cams timed (again) and some head work



before



and after

 

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old fart
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3,641 Posts
Discussion Starter #1,176
she is now so much fun to ride again, I am going to leave her as is for the summer, as i want to do some actual riding this year
but come the bad weather she will be getting head off, new valve guides (still leaking FFS) bit of Stu head magic, re time the cams ( i re fitted the bandit cam sprockets so had less to worry about with the engine trouble/set up)

and then back on the Dyno to get rid of the mid range dip, should be just a case of moving the MJN's up or down a clip.

onwards :)
 

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old fart
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3,641 Posts
Discussion Starter #1,177
I have now done a few more hundred miles since the dyno session, have had to make some very small adjustments
to the pilot air screws to iron out a glitch at 2100k rpms, we had noticed it at the end of the runs, and knew i was going to need to play around to sort it.
i think she is now sorted for the summer,
as for the valve stem seals, since i said i was going to get new valve guides fitted she has stopped smoking at start up!!!! must have heard me talking.
 

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old fart
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3,641 Posts
Discussion Starter #1,178
have now ordered and received a set of APE valve guides ready for changing out the stock ones,

also just ordered some Brembo T drive discs to go with the P4 32 - 36 brembos that i am going to fit.
 

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old fart
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3,641 Posts
Discussion Starter #1,180
rims look good. 12+ cbr1k right?
yep, thats the ones :D

Just took the easy way out of getting pads to fit (and the most expensive!!!!!!!) the P4 32-36 calipers, didnt want to go down the road of having to get a set of cheap thick pads

machined down to fit, i took the road that leads to fuckin outrageous*Brembo 8mm thick Z04 compound race pads see how they go, if not up to road riding then
i might just have to bite the bullet and get some street pads machined to fit.
 
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