main jet has a number but no mark to identify who makes it??

[gixer2000]

So I pulled my main jet because im having some bogging issues and noticed the main jet was labeled 172(hex shape) but had no manufacture name or symbol on it to identify it. I know all manufactures use different numbers to label the jet size but i have no idea who makes this. I want to put in a keihin jet but not really sure what size i should start with. My brother jetted the bike years ago and has no idea who made the jet kit. the bike is a 05 trx400ex. mods are two brothers slip on,air box/no lid,k&n air filter and a timing key(+6* timing).

[JOHNDOE83]

www.jetsrus.com has a jet identifier in their FAQ section.

[CJM]

152-160 main jet depending on elevation and such.

If the jet appears to be a hex shape its most likely a keihin type jet. Not all keihin jets are real keihin jets of course, but most of them work right.

Your bogging is a rich condition most likely, pull your spark plug-should be brown/tan not black (rich) or white (lean).

[gixer2000]

Yeah its rich because the plug is dark grey or light black...lol The bike seems to run ok as long as im at the top end of the gear. if i shift without winding out every gear it just bogs like crazy. Ill go out and buy those jets and see if i can get it tuned. thanks for the info guys

[gixer2000]

According to Google earth the place i ride is about 65 feet above sea level so im guessing ill be on the lower end of those jets you recommended?

[CJM]

Probably will be the same kinda jetting I generally run.

So a 152-160 is what I would buy and try them all out. Start higher then drop it down. Probably will wind up at 152 or 155.

[JOHNDOE83]

Without doing a "plug chop" type reading where youd have to do a full throttle run and kill the motor etc. your not gonna read the plug right at all.

Otherwise your only looking at pilot jet and needle settings on a spark plug if you just pull it out and look at it.

Bogging is a lean condition not a rich condition, rich is a stutter like a rev limiter, bogging is like running out of gas.

[JOHNDOE83]

If its a dyno jet a 175 is equivalent to a kehin 195, 172 is what dyno jet kits usually come with.

If its a minkuni jet a 172 is equivalent to a keihen 208.

So you might be on the rich side depending on which one it is, it could be a aftermarket kehin style jet I have a few of those to with only a number no symbol.

If your still not sure and wanna re-jet it I would do like cjm said and plan on running 160ish main jet, 155 is recommended for stock atvs with a slip on, I would buy 155-180 in incriments of 5, start at 180 and go down.

The weather is changing and it probaly threw off your needle mixture causing a bogg.

[gixer2000]

Originally posted by JOHNDOE83
If its a dyno jet a 175 is equivalent to a kehin 195, 172 is what dyno jet kits usually come with.

If its a minkuni jet a 175 is equivalent to a keihen 210.

So you might be on the rich side depending on which one it is, it could be a aftermarket kehin style jet I have a few of those to with only a number no symbol.

If your still not sure and wanna re-jet it I would do like cjm said and plan on running 160ish main jet, 155 is recommended for stock atvs with a slip on, I would buy 155-180 in incriments of 5, start at 180 and go down.

The weather is changing and it probaly threw off your needle mixture causing a bogg.

Im just going to rejet it. my brother jetted it the first time and basically told me he had no clue what he was doing but just followed the instructions and put in what was sent. The weather is kinda cold here but I still had this issue even when the weather was nice but didn't have the time like i do now to ride it. I just want to make sure I dont blow this bad boy up and have some fun without issue.