Kawi2strokes.com Forum

Enthusiasts from around the world dedicated to the preservation and ritual flogging of the infamous Kawasaki 2-stroke Triples
It is currently Thu Mar 28, 2024 2:58 pm

All times are UTC - 5 hours




Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Sat Feb 04, 2012 12:23 pm 
User avatar

Joined: Sat Jun 11, 2011 10:08 am
Posts: 263
Location: North Shore, Massachusetts
I'm interested in upgrading my stock H2 carbs. The mikuni tm34 carb kit from Niche Cycle seems like a good, comprehensive package. Anyone know how a power jet would affect the tuning and performance of these? I understand the concept. Some sources say it's highly recommended for 2 stroke applications. I guess my confusion is this: why would this improve the tuning characteristics if the proper main jet is installed? Wouldn't it over-richen the main fuel circuit towards WOT when the power jet kicks in? Or are 2 strokes really that thirsty when run at WOT? Or is it a way to lean out the main jet while not risking detonation to improve 1/2 to 3/4 throttle opening? Seems like a redundancy to someone like me with no experience with them


Top
 Profile  
 
PostPosted: Sat Feb 04, 2012 12:47 pm 
Site Admin
User avatar

Joined: Tue Jun 07, 2011 6:37 am
Posts: 10460
Location: Rio Rancho, New Mexico
They just complicate tuning. If you take time to tune the carbs properly, then they do get redundant. (on the street)

_________________
Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........


Top
 Profile  
 
PostPosted: Sat Feb 04, 2012 3:53 pm 

Joined: Tue Dec 27, 2011 11:37 pm
Posts: 726
Location: SUNRISE FLORIDA USA
Im currently running PUMPERS on my non stock H2A. My thought is that at ultra wide open throttle settings there would never be a lean burn condition. However if you're 100% sure that you are in perfect tune........ The plusses are #1 You can use the tube as a float level indicator..HANDY! (You can see at a glance if a carb has run dry or is too high.) And almost as important #2 People always ask "What is that?" Then there's the fact that they turn off, too. :thumbup: More fuel. Cool, and potentialy a safety feature. Its a WIN, WIN to me!

_________________
1972 H2, modified and Tracy bodied. 77 Kawi 1000. Lime green. Cafe. Lester wheels.


Top
 Profile  
 
PostPosted: Mon Feb 06, 2012 5:27 pm 
User avatar

Joined: Sat Jun 11, 2011 10:08 am
Posts: 263
Location: North Shore, Massachusetts
Ja-Moo wrote:
They just complicate tuning. If you take time to tune the carbs properly, then they do get redundant. (on the street)


Are they more useful in race applications? Obviously I couldn't run WOT or near WOT for very long on the street, or keep my license for very long while doing it.

ZERO wrote:
Im currently running PUMPERS on my non stock H2A. My thought is that at ultra wide open throttle settings there would never be a lean burn condition. However if you're 100% sure that you are in perfect tune........ The plusses are #1 You can use the tube as a float level indicator..HANDY! (You can see at a glance if a carb has run dry or is too high.) And almost as important #2 People always ask "What is that?" Then there's the fact that they turn off, too. :thumbup: More fuel. Cool, and potentialy a safety feature. Its a WIN, WIN to me!


Interesting, what type of carbs do you have installed?


Top
 Profile  
 
PostPosted: Mon Feb 06, 2012 6:01 pm 
Site Admin
User avatar

Joined: Tue Jun 07, 2011 6:37 am
Posts: 10460
Location: Rio Rancho, New Mexico
smoff83 wrote:

Are they more useful in race applications? Obviously I couldn't run WOT or near WOT for very long on the street, or keep my license for very long while doing it.



They are more for racing applications. Hot porting can cause a lot of reversion in the intake, so you get a rich midrange. You can lean out the needle, and add extra fuel with the power jet at WFO.

_________________
Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........


Top
 Profile  
 
PostPosted: Mon Feb 06, 2012 6:37 pm 

Joined: Thu Jun 09, 2011 11:25 am
Posts: 3137
The better power jet systems use an electronic valve to cut and open the jet, at certain levels of acceleration/sustained rpms. The latest TZ250 Yamaha's use a part of the timing computer to do a two section valve opening.


Top
 Profile  
 
PostPosted: Mon Feb 06, 2012 7:32 pm 
User avatar

Joined: Sat Jun 11, 2011 10:08 am
Posts: 263
Location: North Shore, Massachusetts
Thanks guys. Makes more sense to me now


Top
 Profile  
 
PostPosted: Tue Feb 07, 2012 4:50 am 

Joined: Tue Dec 27, 2011 11:37 pm
Posts: 726
Location: SUNRISE FLORIDA USA
Smoff83, Currently 34mm Mikuni pumpers. However my engine is not even close to stock and is reed valved. I was just mentioning the features that I like personally.(Like that they hook up to the original throttle and choke cables) I am seldom at full throttle...if ever. I've got a ZX14 for that. I need to also ad that there will be more effort at the throttle due to the stiffer slide springs. I don't notice it anymore.

_________________
1972 H2, modified and Tracy bodied. 77 Kawi 1000. Lime green. Cafe. Lester wheels.


Top
 Profile  
 
PostPosted: Tue Apr 17, 2012 10:05 am 

Joined: Thu Jun 09, 2011 4:22 pm
Posts: 44
Location: Central Ohio
I've had the thought that the power jetted carbs allow fuel to be mixed with air better, because of the two points that fuel enters the airflow into each cylinder. Almost opposite each other.

Instead of one point low down in the air flow.

A valid thought, or izzit useless at these air speeds?
Brett

P.S. I've got 3 power jet equipped Mikuni carbs, new, never used. Bought from someone years ago, who had some triple project, and failed to utilize them... Think his was a kettle?
I put one onto a TM/TS 400 Suzuki projeckt... Haven't finished playing with that one yet...
I think another one went onto my Rickman 250 road racer...
The other one still sits in top of the tool box....


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB® Forum Software © phpBB Group