Plug color

[Alf]

Please, details about the Randy carb kit

By a general rule, you must set first the main jet before touching anything more

Please help my understanding. When working on jetting in the past (mostly dirt bikes) we started with pilot jets and worked up from there? Because of the overlap. Is this different on four cylinder street bikes? Thank's for your input.

Kurt

All that I´ve read and learn since I was a kid was starting with main jets. Even with my RD 350 that I raced a couple of years the first thing was getting the correct main jet, and after trying to get the most engine power performance in all the engine power delivery. And I try to get the fatter horsepower, with plenty of low and midrange, not the maximum power form the bikes

The pilot circuit control the idle and its working range is from idle to 1/4 throttle opening, so I don´t understand that method.

[Alf]

So I turned the mixture screw IN a half turn. Blip test is solid, as idle returns normally with no hang or drop. Stock kit for 92 -
#110 Main Jet
#155 Air Pilot Jet
#42.5 Fuel Pilot Jet
from RPM. Left stock needle in, not adjustable.
Still rumbles on the deceleration at 1500 rpm,(and by stumble I mean I can feel a distinct vibration on deceleration under my ass while coming to a stop, my 89 does not do this) maybe I need to lube engine mounts, a little leery to do that though not too sure of my skill set. Anyway thats all I have. Thanks for the replies.

The specs are the same that the  European OE settings, so the bike must run correctly
You have not specified 2 things:
- the mixture screw settings (leave it around 2 1/2 and 3 turns out)
- Are you diaphragms in good nick?. The symptoms (too rich, engine stumbles and vibes) are from damaged diaphragms.  The good news is that the problem is cheap to repair. Watch my web, tips & fixes section

Or it is simply a dirty air filter

[Tapartacus]

Hi Alf thanks for the reply. Have been to your FJ site, lots of great info there, great site. I've had the carbs apart and the diaphragms are in good "nick" Like I said, was thinking some vibration somewhere on the bike at 1500 is giving me the sensation that the engine is stumbling. When I ride down my street without a helmet on tuck my head under the fairing and listen to the engine(@ 1500 rpm) all I hear is the purr of 1188 cc's winding up. I think I must actually going crazy.
Andrew

[Alf]

Its very important the chain state and alignment too

[ribbert]

When I noticed roughness during decelleration on my '93, it was frozen motor mounts.

I just used these for the first time since doing my engine mounts some time back, very satisfying seeing the old grease pushed out followed by the fresh stuff.

Noel

[Tapartacus]

Noel did you put that grease nipple there? And can you explain how greasing the collar stops the engine vibration. I just don't get it, I would understand if the mount was rubber.
Andrew

[SlowOldGuy]

That collar needs to move freely to let the rubber at the other end of the mount (on the frame side of the mount) aqbsorb the vibration.

Do a search for greasing the motor mounts.  When I first got my '93, it was silky smooth.  But it gradually degraded, picking up a bad decelleration vibration.  The engine felt rougher than my solid mounted '85. 

I rode Chris Murphy's very low mileage '92 at a spring rally and instantly knew something was wrong with my bike.  I re-synched the carbs multiple times to no avail.  When I got back home, I started experimenting with the motor mounts.  When I loosened them, the vibration seemed to be less.  I finally tried to remove the front mounts to inspect them and possible replace them.  They were frozen in place with corrosion.  I came up with a tool to drive them out, cleaned and greased them up and it been back to sliky smooth since.  Bob N. did a great job of documenting a similar tool and the procedure somewhere in the FILES section.

DavidR.

[racerrad8]

... Bob N. did a great job of documenting a similar tool and the procedure somewhere in the FILES section.

DavidR.

Late model motor mount service file

OR

Late model motor mount service file II


Randy - RPM

[Tapartacus]

Can anyone enlighten me on how to take the bolts off? I've tried with a 17mm 1/2 in socket wrench and just about pulled my bike over, those things are on tight!

[yamaha fj rider]

Please, details about the Randy carb kit

By a general rule, you must set first the main jet before touching anything more

Please help my understanding. When working on jetting in the past (mostly dirt bikes) we started with pilot jets and worked up from there? Because of the overlap. Is this different on four cylinder street bikes? Thank's for your input.

Kurt

All that I´ve read and learn since I was a kid was starting with main jets. Even with my RD 350 that I raced a couple of years the first thing was getting the correct main jet, and after trying to get the most engine power performance in all the engine power delivery. And I try to get the fatter horsepower, with plenty of low and midrange, not the maximum power form the bikes

The pilot circuit control the idle and its working range is from idle to 1/4 throttle opening, so I don´t understand that method.

It sounds like you are working from full throttle down. We worked from idle up to full throttle. For desert racing we wanted a crisp low and mid range then a  just little rich on the main for those long wide open sections.

Kurt

[Alf]

Thanks for the explanation. Everyday I learn something new 

[Tapartacus]

Can anyone enlighten me on how to take the bolts off? I've tried with a 17mm 1/2 in socket wrench and just about pulled my bike over, those things are on tight!

oh ya and why do I have to take all 3 bolts off if its just the one I want to pull out?

[ribbert]

Noel did you put that grease nipple there? And can you explain how greasing the collar stops the engine vibration. I just don't get it, I would understand if the mount was rubber.
Andrew

Just to add to DavidR's answer to this question.  The grease nipples ( yes, I did put them in ) are only for maintenance AFTER you've done the fix as described in the Files, fitting them will not cure the problem once they are seized.

I've made lots of improvements to my bike but the difference the engine mount fix made was the best by a country mile.  We are talking zero vibration from 3500 rpm up and very mild low range vibration below.

I've never known who to thank before for discovering this gem.  David, thankyou, thankyou, thankyou.

Noel

[SlowOldGuy]

Hey Noel,
You're very welcome!

Believe me, I was also extremely happy to find and correct the source of the annoying vibration. 
Feels almost as good to share the information with others and see the benefit they get from it

DavidR.

[yamaha fj rider]

Can anyone enlighten me on how to take the bolts off? I've tried with a 17mm 1/2 in socket wrench and just about pulled my bike over, those things are on tight!

oh ya and why do I have to take all 3 bolts off if its just the one I want to pull out?

Should not be that tight, sounds seized. Try heating the nuts a little? Remove all three bolts and the brackets. You will understand. Do you have an air impact or a neighbor who can help. Be careful when removing these or you can damage engine your cases (big hammer is not the answer). Hope this helps.

Kurt