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Post by monza on Apr 29, 2009 0:10:23 GMT
Ok, so I need a sanity check. Im trying to dial in my Parmakit smallie, and im getting frustrated with the jetting. I just keep going up and its still lean.
The engine: Parmakit 130, full circle, Mikuni VM28 flat slide, Parmakit ignition (25 deg initial), and a (temporary) Simonini D&F exhaust.
Current jet is a 380. To me (coming from only tuning delorto carbs before) that sounds HUGE, but is it? Should I expect something like a 450 and that is normal for this sort of setup?
Wallet is thinning everytime I go to the shop...
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Post by jonnysnatchsniffer on Apr 29, 2009 7:06:02 GMT
fucking huge 380 is the same as a dellorto 168 and on a 28mm carb is a little on the large side you wanna start about 220/230.
it might be lean for another reason
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Post by bigchap on Apr 29, 2009 7:51:50 GMT
make sure you use brass mikuni jets,the plastic ones are notorious for being very inaccurate on their sizes and if you over-tighten them they get smaller because the walls pinch in.
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Post by monza on Apr 30, 2009 3:11:01 GMT
yeah, I have the brass Mik jets, they had the plastic ones, but decided it was better to get the real deal.
Yeah, i thought about it being lean for another reason. I pulled the engine and checked everything over, head, base gasket, exhaust, intake bits, seals...its all buttoned up.
I started at 180 and did 220, 240, 280, 340, and now 380!
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Post by jonnysnatchsniffer on Apr 30, 2009 18:33:50 GMT
380 is far too big, you gotta have another problem im sure, i could be a nob and ask if ya seals are in the right way round but i wont.
try it with no main jet and see what happens if its still lean then your needle is very lean (providing everthing else ie air leaks is ok) you can get richer neeldles and needle jets
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Post by soosh on Apr 30, 2009 19:24:38 GMT
Hey mate,you say you wont be a nob and ask about seals,a mate stuck his GP motor back together and wondered why his crank had play in it,thought it would be ok when it warmed up.I wasnt gonna ask him if he put the bearing race on the crank.............he found it under his packet of rollies!!
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Post by breezer on Apr 30, 2009 19:31:00 GMT
Hey mate,you say you wont be a nob and ask about seals,a mate stuck his GP motor back together and wondered why his crank had play in it,thought it would be when it warmed up.I wasnt gonna ask him if he put the beering race on the crank.............he found it under his packet of rollies!! Nik again? ;D |
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Post by monza on May 1, 2009 3:26:03 GMT
i could be a nob and ask if ya seals are in the right way round but i wont. just to be safe, I pulled the fly and checked...that ones in right. picture I took when building it shows the clutch side is in right. ugh, was hoping that it was something easy like that. |
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Post by jonnysnatchsniffer on May 1, 2009 14:40:16 GMT
mmm still something wrong tho 380 is ts1 territory on a 35mm carb, i will be using around a 250 with a 30mm tmx on my parma, check the carb rubber and also the blankoff plate.
did you open up the transfers on the barrel as far as they would go ? as when i did that, where the indent bit is on the engine gasket face is, the sealing area was gone.
other than that im stumped.
have you tried it with no main jet yet ? as the needle and needle jet are what lets the fuel to the main jet, it might be that even if you put a 500 main in they wont flow enough fuel thru with that combination of needle and needle jet, so not having a main jet in will let you know if this is the case
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Post by monza on May 2, 2009 15:00:28 GMT
well, checked the intake rubber, and it wasnt super tight, so sealed with some RTV and then tightened good, but problem is still there. Checked the blocking plate. sealed with RTV when I built the motor and cap bolts are tight. Im going to try taking the main out and see what it does. Its been raining, so testing is spotty. This Mikuni is new to me...should the needle come almost completely out of the needle jet when the slide is WOT? seems to sit low to me. Maybe Ill play with clip setting to see. Probably should have gotten a powerjet model  |
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Post by monza on May 2, 2009 17:10:43 GMT
Ok, so just had a thought. I have a fuel pump, but its not hooked up right now...could this be it?  Are you guys needing a pump? |
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Post by unreliablesc on May 2, 2009 19:05:02 GMT
Ok, so just had a thought. I have a fuel pump, but its not hooked up right now...could this be it? Are you guys needing a pump? you shouldn't need a pump if the carb is lower than the tank. i got the opposite problem btw, cant get it to lean out. it's still four-stroking badly if i don't ride it like a madman. manjet is fine, but the midrange is super rich, even with the smallest pilot i can get my hands on, and the leanest needle on top clip |
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Post by soosh on May 3, 2009 12:18:48 GMT
Hey mate,you say you wont be a nob and ask about seals,a mate stuck his GP motor back together and wondered why his crank had play in it,thought it would be when it warmed up.I wasnt gonna ask him if he put the beering race on the crank.............he found it under his packet of rollies!! Nik again? ;D No,not this time. |
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Post by breezer on May 3, 2009 12:24:42 GMT
;D ;D ;D
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Post by monza on May 3, 2009 16:29:33 GMT
ok, so im going to rule out an airleak, as it doesnt run erratically, perfect idle, great midrange, the only problem is main jet for WOT. I have checked the whole motor, if its a leak, its internal.
What im wondering now is whether its the carb. Checking on a TM28 I find that it has a 'bleed' type needle jet. Im assuming its supposed to have a 'primary' type with the protruding neck on it for 2t applications.
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Post by monza on May 21, 2009 3:07:40 GMT
Just to follow up on this...got the problem fixed.
On the Mikuni TM28, they ship it with a needle jet that is optimized for 4-stroke motors. Get the "Primary Choke" type needle jet with the "hat" that protrudes into the bore, and viola, problem solved. Got my jetting to a reasonable #240 and the thing runs tits.
Over the weekend I raced a mate with a highly ported 210 & new "226 Vintage" pipe. We were neck and neck. Once I get a proper pipe on it (hammerzombie) it should be freaking awesome.
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Post by soosh on May 22, 2009 17:15:15 GMT
It will be,kin ace! Is ur parmakit standard porting?
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Post by monza on May 26, 2009 12:01:36 GMT
I opened up the transfers but left the ports in the jug alone. Im not skilled enough to be fecking with em ;D
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Are you guys needing a pump?