Jetting Help

General Bike chat
Post Reply
gwade
Posts: 3
Joined: Wed Dec 22, 2004 3:10 am

Jetting Help

Post by gwade »

Greetings from a new user in the States. I have an 03 VTR that I finally fitted with a Yoshimura RS3 Zyclone. I just got the bike from getting jetted (Dynojet kit) with the following settings:

Pilot #50
Mains # 185/190
Needle 4th notch down

The guy who did the jetting is very well respected here for carburetion work, but the thing is a total bear to start. Even he seems stumped.

The dyno shows a nice power curve and the air fuel is perfect (12-13) from 5K up. The AF is a bit lean from 3.5K to 5K (no higher than 15).

It just takes forever cranking over to start, and requires me to crack the throttle to get/keep it going.

Has anyone had a problem like this??? Please help!
gwade
Posts: 3
Joined: Wed Dec 22, 2004 3:10 am

Post by gwade »

Follow up if this helps. Came into my garage this morning and it reeks of petrol. Do you think something is causing the fuel to continue to drip slowly into the engine and cause flooding after it sits?
User avatar
cupasoop
Site Admin
Posts: 2687
Joined: Sat Mar 06, 2004 11:02 pm
Location: Ayrshire, Scotland

Post by cupasoop »

I've been downstairs in the work drinking beer all afternoon so I'm a bit fuzzy. Does this sound like the pipes have been swapped under the fuel tank? If you have had your tank off, check the thick black pipes that connect under the fuel tank have been put on the right way. It's a common problem that catches folk out all the time. Have a search back through the posts on here for a full explination. The pipes are identical but do two different jobs. Try swapping them around.

Am I right or am I in a beer induced state of greatness.
Rich.

Image
4bangthis996
Posts: 38
Joined: Mon Nov 24, 2003 6:07 am
Location: Orlando, Florida. the shity states

Post by 4bangthis996 »

yeah, try that first. the little hose goes on the back of the pet rock(tap) not the front of it. second if this doesnt help on the bottom of the carbs there is a fuel mixture screw, this should be turned all the way in then turn it 3 full turns out. try thid and see if this works
Adeptus Mechanicus
vtrillini
Posts: 6
Joined: Sat Dec 18, 2004 5:54 am
Location: usa

Jetting Help

Post by vtrillini »

Drop to a max of a 48 pilot jet or go back to the OEM 45 pilot jet and OEM air filter. Check that both enrichener fittings and slides are installed properly, and for air leaks (with WD40 or soppy water). 2.5 turns out on the mixture screws should be more than adequate, and recheck syncronization with a mercury stick or electronic gage. I try to keep mine within 1 cm versus the 2 cm the manual allows; also check it at 500 rpm, around 1400 (where I keep my idle speed) and again at 4500 ~ 5000 rpm.

I'm not sure what needles your running but I just shimmed the OEM needles up .061", kept the 45 pilots, run the same 185/190 mains and set the mix @ 2.5 turns out or even less using a exhaust gas meter (not A/F). With this home brew jetting, 2Bros aluminum slip-ons, and hogged out collector restriction (opens right side up more), it was pumping out almost 103 HP and 70'# corrected on a Dynojet 250 (I think) at 30,000 miles (now at over 50k miles). I also use Mobil 1 15W-50 auto grade synthetic oil and a Purolator PL14620/PL14610 synthetic media premium auto filter (see http://motorcycleinfo.calsci.com/Filters.html).

BA
User avatar
dkt1376
Posts: 82
Joined: Fri Sep 17, 2004 7:52 pm
Location: plymouth

Post by dkt1376 »

i have just had my bike dynojetted and set up on a rolling road,
mods include, KnN filter,air box modification, dynojet kit and viper cans and it is now running 115.7bhp at the back wheel, im not shure what jets he used but i will ask him and let u know as soon as he gets back to work.
a landrover d2 and a ktm, i had to have a honda to restore relability in my life.
vtrillini
Posts: 6
Joined: Sat Dec 18, 2004 5:54 am
Location: usa

Jetting Help

Post by vtrillini »

"IS 115.7 BHP AT THE BACK WHEEL TO MUCH?"

Which make and model dyno was your VTR tested on? 115+ HP with the limited mods (what do you mean my "airbox mod"?) seems very optimistic. What was the torque and did he print you a output graph? A well run in VTR with basic mods usually is in the 102~107 range with about 70'#.

BA
User avatar
dkt1376
Posts: 82
Joined: Fri Sep 17, 2004 7:52 pm
Location: plymouth

Post by dkt1376 »

very sorry its running 115.3 at the back wheelImage

hope this proves it
a landrover d2 and a ktm, i had to have a honda to restore relability in my life.
User avatar
dkt1376
Posts: 82
Joined: Fri Sep 17, 2004 7:52 pm
Location: plymouth

Post by dkt1376 »

sorry the pic is a bit big and a bit fuzzy.
the torque figure is 72.2 ft-lbs.

the air box mod is to run two short bell mouths in the air box. buy a front bell mouth and fit it to the rear carb, it will improve throttle response.
hope that helps.
a landrover d2 and a ktm, i had to have a honda to restore relability in my life.
vtrillini
Posts: 6
Joined: Sat Dec 18, 2004 5:54 am
Location: usa

jetting help

Post by vtrillini »

It is not that I doubted the reading your stated but simply that output figures can vary significantly (i.e., as much as 20%) depending on the type of dyno (eddy current [Factory's] versus electronic load [Dynojet] that can differ by 12%+), the model number, operator's experience and skill, whether the computer was connected to the coil/rpm output (i.e., rpm versus mph; yours was not based on the graph), weather conditions, and if the readings we corrected for baometric pressure, temperature and humidity per industry standards.

BA
User avatar
Stormin Ben
Posts: 1234
Joined: Sun Dec 01, 2002 12:23 am
Location: Birmingham

Post by Stormin Ben »

And more importantly, what the hell were you doing getting your bike dyno'd at 6:11 AM !!!!!!!!! :lol:

Ben
Post Reply