Should I rejet?
- Thread starter EZRider76
- Start date
Sorry my bad on the pilot jet (dyslexic) some times. Awks right!
Mikuni and Keinin jets have stamps on them next to the #'s Mikuni's have a box shape Keihin's have a star shape. then there are off brands. (don't know) if dyno jets have any marks on them.
Hope you get it figured out.
Mikuni and Keinin jets have stamps on them next to the #'s Mikuni's have a box shape Keihin's have a star shape. then there are off brands. (don't know) if dyno jets have any marks on them.
Hope you get it figured out.
yeah, ive seen the marks on factory jets, its just sooo hard to nail down ALL the other knock offs that are floating around out there. is there a tool, like a wire diameter tool to measure the size of the jet??? laugh if you want but, when i change my main, i run a torch head cleaning tool in the orifice on some of my older jets to clean out the dust and crap from setting in the garage. those things have about a hundred wire sizes and i didnt know if there was a similar type of tool to accurately measure???Sorry my bad on the pilot jet (dyslexic) some times. Awks right!
Mikuni and Keinin jets have stamps on them next to the #'s Mikuni's have a box shape Keihin's have a star shape. then there are off brands. (don't know) if dyno jets have any marks on them.
Hope you get it figured out.
Be careful with torch tip cleaners, they are actually like a file and would actually enlarge the jet slightly. I'm sure there is some kind of wire gauge tester, where to get it and cost, would just be cheeper to get genuine jets, problem solved. Buy once, cry once.
i know what you mean about the tip cleaners. i run em in and out, thats it. as far as factory jets man, i got about 50 of them. factory, aftermarket... just a collection from all the various carbs ive rebuilt. some are old enough that i cant even read the numbers any more. got them set aside so i dont try to use em. i just wish i could find a tool to measure them. ive looked but i cant find much on it.
Ok, here are some photos to prove my sanity...well, what's left of it at this point. I will say this, I got the best quality I could, and they are as clear as I could get them....50 pics on phone to prove it. Also, I did notice on every part (needle, pilot, slide, main jet) that there was that box inside a box symbol stamped just before the number. I think that is what has been making it so difficult to really determine the numbers. So anyhow, without further ado...
needle and seat 2.8, main jet #150
pilot #50
needle is set at the middle clip position
So, now this brings up some more questions, a #50 pilot??? The largest I've read you fellas talking about is 35. I guess I will also add, on the air screw, I turned it in 1.75 turns...of course then turned it back out 1.75 turns. Also, and I don't want to add to more confusion, but I read a lot about some guys going without the airbox lid, other than possibly allowing more air thru, what is the advantage of this? Wouldn't running without the lid allow dirtier air thru? Oh yeah, one other thing, the air filter is a stock air filter from the Yamaha dealer, pre-oiled. My next step is to run a compression test and check out the plug...gotta read up on the plug chop first though to know what I'm doing there. Just gonna check it out, not actually gonna do the exercise...other than the plug inspection.
needle and seat 2.8, main jet #150
pilot #50
needle is set at the middle clip position
So, now this brings up some more questions, a #50 pilot??? The largest I've read you fellas talking about is 35. I guess I will also add, on the air screw, I turned it in 1.75 turns...of course then turned it back out 1.75 turns. Also, and I don't want to add to more confusion, but I read a lot about some guys going without the airbox lid, other than possibly allowing more air thru, what is the advantage of this? Wouldn't running without the lid allow dirtier air thru? Oh yeah, one other thing, the air filter is a stock air filter from the Yamaha dealer, pre-oiled. My next step is to run a compression test and check out the plug...gotta read up on the plug chop first though to know what I'm doing there. Just gonna check it out, not actually gonna do the exercise...other than the plug inspection.
As to the air box, it allows all air through, dirty or not, thing is without the lid more air gets through because it breathes better.
By adding more air, you can add more fuel, result = more power.
By adding more air, you can add more fuel, result = more power.
Ok, that's makes sense, more air means you need more fuel, to keep the AFR balanced, which gives you more power...but that definitely raises more questions. For now, I'll keep to the topic at hand and ask again, why is my Main Jet # so low and my Pilot so high? Remember, this is a 28mm carb and I don't know if any engine modifications have been done. The PO told me he was "setting it up for racing, had a big bore kit installed and now it is a 252cc engine." I'm not completely buying it, and I know the only way to truly know is to take the top end off and measure, which I don't want to do if I really don't have to. Basically though, this "little" Blaster is going to be trail ridden and is supposed to be for my girlfriend...and of course for me when she doesn't want to go riding and I don't want to play in the mud holes.
that show you have a good strong coil!!! and to your jets? thats a factory mikuni jet, at least it looks like one with the square symbol. also, your 150 looks like every mikuni jet i have numbered 230-320. i dont see why you couldnt just get a 260-290 main and try them. starting with the 290 of course (little rich maybe but, safer to start with.) the pilot jet resembles mine. get a 32.5 - 35 and start with the 32.5 first. leave the needle on the third clip to test. read up on plug chops, theyre not that hard, just need a good vise and hacksaw.
ah, did you ever read this?
http://www.google.com/url?sa=t&rct=...ua39Dg&usg=AFQjCNE3K2CQtsXMB1vlCi74yJyZJ-GiXg
http://www.google.com/url?sa=t&rct=...ua39Dg&usg=AFQjCNE3K2CQtsXMB1vlCi74yJyZJ-GiXg
Ok, here are some photos to prove my sanity...well, what's left of it at this point. I will say this, I got the best quality I could, and they are as clear as I could get them....50 pics on phone to prove it. Also, I did notice on every part (needle, pilot, slide, main jet) that there was that box inside a box symbol stamped just before the number. I think that is what has been making it so difficult to really determine the numbers. So anyhow, without further ado...
needle and seat 2.8, main jet #150
pilot #50
needle is set at the middle clip position
So, now this brings up some more questions, a #50 pilot??? The largest I've read you fellas talking about is 35. I guess I will also add, on the air screw, I turned it in 1.75 turns...of course then turned it back out 1.75 turns. Also, and I don't want to add to more confusion, but I read a lot about some guys going without the airbox lid, other than possibly allowing more air thru, what is the advantage of this? Wouldn't running without the lid allow dirtier air thru? Oh yeah, one other thing, the air filter is a stock air filter from the Yamaha dealer, pre-oiled. My next step is to run a compression test and check out the plug...gotta read up on the plug chop first though to know what I'm doing there. Just gonna check it out, not actually gonna do the exercise...other than the plug inspection.
Hmmmmm. Well, My 30 oko which is the 28 bored out took a 158 main so i don't think a 150 is that far off. The pilot is close to IMO I had a 48 in the 30oko. Of course the oko's are a keihin knock off so i am kind of stumped on this one!
Hoooowwwww the HELL did this thing even start let alone run without backfiring and spitting and sputtering???? LMAO...I've seen fouled plugs before from my old Camaro, but this is the worst I've ever seen.
Well it sure isn't lean! I'm not buyin it's a 252cc. Not with those jets!
They probably tried to compensate the pilot with the main, Maybe???
Pilot will feed fuel thru all of the throttle range but only effects idle range the most.
High pilot numbers usually indicate air leaks being compensated for. But that main is really low for the blaster motor in stock form. Unless they did a taboo and drilled it out to fatten the jet out. I've heard some will do that.
But like I said before the jetting will be similar to the stock carb, But the main more than likely will need to go up one size if at all from my experience with mine on a stock motor.
Pilot will feed fuel thru all of the throttle range but only effects idle range the most.
High pilot numbers usually indicate air leaks being compensated for. But that main is really low for the blaster motor in stock form. Unless they did a taboo and drilled it out to fatten the jet out. I've heard some will do that.
But like I said before the jetting will be similar to the stock carb, But the main more than likely will need to go up one size if at all from my experience with mine on a stock motor.
They probably tried to compensate the pilot with the main, Maybe???
Pilot will feed fuel thru all of the throttle range but only effects idle range the most.
High pilot numbers usually indicate air leaks being compensated for. But that main is really low for the blaster motor in stock form. Unless they did a taboo and drilled it out to fatten the jet out. I've heard some will do that.
But like I said before the jetting will be similar to the stock carb, But the main more than likely will need to go up one size if at all from my experience with mine on a stock motor.
im ok with the 'stock carb' part but, stock for what? this is a 35mm mikuni vm. the russian link i posted mentioned something about the jets being around that 150 number but to feed a 650 sumthinoranother??? question is, can he swap out those jets with the standard mikuni jets. i think so. its worth a shot eh?
Well slap me and call me Susan, I have finally seen my carb. On page 2 of that document/link, the watermarked picture of the carburetor...that is indeed the carb I have (this of course is being judged on account of the cap and the cable attachment). The others have been close, but this one is just about perfect. The only difference is the fuel supply nipple on my is part of the casting of the body, not a brass fitting. Anyhow, so finally, it appears my carb came on a 650cc russian engine...
...definitely gonna have to rejet. Also I find it odd it says the Main was #200 and the Pilot was #60...that's pretty damn close boys. I will have to read more later though. Kudos my friend for finding and linking that, I hadn't seen that yet...my archives are relatively small. :-[
do not pay much attention to carb settings that came off of multi cylinder machines
disregaurd any info here about keihin/oko jet #'s
they are not the same
throw genuine mikuni 32.5 pilot and a 270/290 main jet in that mikuni 28 and she will at least start and run to allow fine tuning!
or i'll run a honda sticker on my blaster for the rest of the season
disregaurd any info here about keihin/oko jet #'s
they are not the same
throw genuine mikuni 32.5 pilot and a 270/290 main jet in that mikuni 28 and she will at least start and run to allow fine tuning!
or i'll run a honda sticker on my blaster for the rest of the season
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BAHAHAHAHAHHAAHAAAAHAHHAAAAAAHAHAHAAAA!!!!!!
As for the rest, yes, I was going to throw it out the window and rejet for sure. I just found it quite coincidental that the jets were the size that I was looking at...just kinda made what I was saying seem a little more feasible. Also, I gathered by previous posts that relating to Keihin/oko/other carbs was going to be more of a nightmare and add to more confusion than anything, and that's the last thing I need. B) I pretty much figured the smaller jets was for the bigger cc's and multi-cylinder too, but it is nice to know that now I have a back up carb for my 550ltd. I:I
Thanks for all the help fellas, I will keep you all posted on the rejetting. Now I just need to find something else to start a new thread on.
I'm sure I will. :-[
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Keihin carbs are great, their jetting is a lot easier to pin point vs mikuni. What I mean is, their jets go in smaller increments the mikuni does so they are truely fine tuned. In the same breath, mikunis are very easy to work on and have a great track record. I hope you get your jetting squared away and keep us posted. Good luck!
