High speed stumble...? Scrambler. - Page 2 - Triumph Forum: Triumph Rat Motorcycle Forums
» Main Menu

Discussion Forums
 » Twins
 » Tiger
 » General
 » RAT

Features
 » Blogs

Motorcycle.com Links

Contribute
 » Photo

Motorcycle Forums
» Insurance
» Sponsors
Motorcycle.com Classifieds!
» Our Partners
»ATV Reviews
»Motorcycle Games

Twins Technical Talk Technical Talk for Hinckley Triumph Twins: Bonneville, T100, Speedmaster, America, Thruxton, and Scrambler.

Reply
 
LinkBack Thread Tools Display Modes
Old 12-12-2012, 08:23 PM   #11 (permalink)
Premium Member
Site Supporter
Grand Prix 250
Main Motorcycle: 07 Triumph Scrambler
 
Join Date: Sep 2012
Location: Orlando-Jacksonville
Posts: 43
Other Motorcycle: 07 Honda ST1300A
Quote:
Originally Posted by Firstman View Post
I have been on a 450 mile road trip thinking about your issue. A constant rich/lean mix would show up on the plugs, but something killing the fuel would not. I worked on a carbureted bike that had a similar issue, at 65 mph the bike would stumble. I was able to reproduce the stumble reproduce the issue at certain RPMs, it turned out to be a piece of dirt that looked like a single flake of pepper that would lodge itself in the main jet only when X amount of fuel was being consumed.


Sent from my iPhone using Motorcycle.com Free App
I really appreciate this. I'm coming to the conclusion that it's a fuel interruption problem too, either as you describe or (hopefully) in the petcock or that screen I understand is near the left carb. I'd really like to rule that out before getting into the carbs. I did take the top covers off the carbs and the - I guess those are what's called the diaphragms- the thin black rubber membranes through which the needles and springs go; were in fine shape.

I really want to get a good understanding of how the Keihins function and how to trouble shoot them, but I am not there yet, so I'm being cautious. Also because the bike really runs well in all other ways- starts fast, idles nicely, no backfiring, no stalling; so I don't want to screw that up. And I am capable of screwing it up.
BalancePoint is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-12-2012, 09:03 PM   #12 (permalink)
Senior Member
Formula Extreme
Main Motorcycle: 2008 T100
 
bluesforchallah's Avatar
 
Join Date: Sep 2008
Location: Seattle, WA
Posts: 865
It may just be that the jets either need cleaning or replacement. I had chased a fuel delivery roast for months only to find myself right back at the same jetting I was before the problem started and everything seems to be at 98% better. Still have a slight hiccup, but over all, the bikes running much better.

Jets are cheap and easy to replace. While you have the pilot jets out, you may want to pull the air mixture screws, being careful not to lose the small spring, washer or rubber 'O' ring (but first, screw the mixture screws in and count how many turns it takes before they come to a dead stop[This will be the number of turns you set the screws to when you replace them]). With the air mixture screws out, blow carb cleaner up into the carb bodies until the carb cleaner comes out the other hole (i.e. shoot cleaner into the air mixture hole until the carb cleaner is coming out the pilot jet hole and vise versa), then before the carb cleaner has a chance to evaporate, hit it with compressed air trying to blow out any possible obstruction. Then make sure when everything goes back together, the air mixture screws are set at where they were before they came out.
__________________
Chris
BIR# 309
08 T100 with AI removed, K&N Pods, BC Predators, 145 mains/42 pilots, no shim, -1 turn out @ sea level, green springs
bluesforchallah is offline   Reply With Quote
Old 12-13-2012, 01:01 AM   #13 (permalink)
Premium Member
Site Supporter
Minitwins
Main Motorcycle: R1200GS
 
Join Date: Dec 2012
Location: Tucson
Posts: 17
And if you want to feel more comfortable with a carb before tearing into yours, find a shade tree mechanic in your area, give him $20 to teach you the basics on an old carburetor. While yours will be different, pulling the jets out and such on a workbench will give you the confidence to go forward on yours.


Sent from my iPhone using Motorcycle.com Free App
Firstman is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
High speed on a scrambler ? meloman Twins Talk 35 10-22-2011 02:48 AM
Stumble - Power loss at high speed Mongo007 Trophy 4 08-16-2010 12:26 PM
2006 Scrambler Engine Dies at high speed. ***? CTW Scrambler Twins Technical Talk 6 01-29-2010 06:55 PM
low speed stumble DCM Trophy 5 04-11-2009 11:09 PM
low speed stumble? SpeedTrippin Speed Triple Forum 8 08-23-2008 01:39 PM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 07:11 PM.



Motorcycle News, Videos and Reviews
Honda Grom Forum Harley Davidson Honda 600RR Kawasaki Forum Yamaha R6
1199 Panigale Roadglide Forum Honda CBR1000 Vulcan Forum Yamaha R1
Ducati Monster Harley Forums Honda CBR250R ZX10R Forum Star Raider
Suzuki GSXR V-Rod Forums Honda Shadow Kawasaki Motorcycles Star Warrior
SV650 Forum BMW S1000RR Honda Fury Kawasaki Versys Drag Racing
Suzuki V-Strom BMW K1600 Triumph Forum Victory Forums Sportbikes
Volusia Forum BMW F800 Triumph 675 MV Agusta Forum Streetfighters

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

Search Engine Optimization by vBSEO 3.6.0