Checking Others work....

[k_902]

Well I bought my GPZ400R about 2 years ago. It was all stock and fresh out of storage in Japan (in someones garage for about 6 years) . It got shipped over and delivered to Mike's place. Now Mike has been rebuilding bikes for about 20 years and has been a respected local drag racer for 10. His done great work with my uncles CBR600 and a nice guy to boot. So needless to say when I bought the bike from him, I trusted the work he done to it as well. (all fluid change and overhaul, carb cleaning etc... normal out of storage stuff)

The first year I had the bike it ran great, till the tail end of the riding season. And the bike started fouling the plugs really bad. Came to the conclusion that it was running too rich. So back to mike for a re-cleaning of the carbs. All said and done it worked again..... Wait.... 2 weeks later the plugs when again.... So I swapped out the plugs and drove it till the end of the season.

So the start of this year I decieded that I was through with other people working on my toys. I never let someone else do the work on my cars so why my bike? So this summer the bike was still running rich no matter how you adjusted the carbs. Black smoke and soot all over the place.
And last Friday in rush hour in town with the bike totaly flooded out, well that was the last straw....

Got the thing started after sitting for 45 mins got home, and took the carbs off. Took everything apart and cleaned it myself. Pulled up the specs for the carbs, and well dear old Mike had put the wronge jets in the wronge carbs.... 4 carbs with miss matched needle jets, main jets, you name it.

Soooo, Put everything back together according to the specs, started her up and off I went. Talk about a totaly new bike. No more bogging down in low rpm, and pulls harder then before, as well as much more responsive.

I Learned that even with years of rebuilding bike and racing them, you can still make a mistake. So always check things over yourself, or better yet, learn to do everything yourself....

Sorry I just had to Rant about it....
Kyle

[QKENUF4U]

ok good for you but did you take into consideration that the "WRONG JETS" etc. where actually correct since the bike has a full header etc. if you put STOCK size jetting back in the bike then mikey just didnt TUNE it correctly and your prob. on the LEAN side now, better keep an eye on the plugs and make sure they are burning correctly (gold/brown/tan color).

[k_902]

I'm gonna pull the plugs back out in a couple days to see how they are after riding for a bit. Last thing I need now is to burn a hole in my pistons. As for the jets, they were the right ones but were miss matched in the carbs.

The Specs show Main Jets are 102 for carbs 1&4
Main jets are 105 for carbs 2&3
Jet Needle N27L ===== 1&4
Jet Needle N27P ===== 2&3

Mike had the main jets mixed up a bit with 102 in 1&3.
And the Jet Needles were N27P in 1&2.

I think he did a good job cleaning but didn't relize that the componets were a little different from carb to carb.

Do you know why the carbs would have different jetting from 1&4 to 2&3? I found this very interesting but can't think of a good reason why.

Thanks for any help!!
Kyle

[elr658]

Staggered jetting is often found on CBXs, Kaw triples and Tridents as their middle cylinders are barbeque pits.

[QKENUF4U]

elr is right, the middle cylinders run a bit hotter so you have to run them a bit fatter/richer

[k_902]

Right on. Thanks for all the great information.

Kyle