Help with HIGH engine RPMs

[trapper_canada]

Hi all...I have been reading these forums for a little while now...but this is my first post.

I bought a 79 XS11 a few weeks ago. I have an 03 Intruder but cause its so new there is nothing to play with!

A History.

So I found this poor and lonely XS11 at an auction. It was in rough shape. I have spent the past couple weeks going through it and doing what I can (I am the farthest thing from a mechanic!). I replaced all the fluids (except brakes which will be next) and filters...put in a new battery...and some other misc items.

The Carbs were in bad shape....mucky...springs wouldn't recoil...nothing. So I took the carbs off and brought them into the Yamaha dealership to get them to clean them up (didn't want to screw them up). They had to replace one of the idle mixture screw tips (it was broken)...said the others should be replaced for efficiency...perhaps I will do that later. While the carbs were off I thoroughly examined the rubber of the carb boots...no cracks have gone through.

So that brings me to my problem....when I start the bike it starts to Rev...VERY HIGH....I have to kill it to save the poor engine. It did this when I first got the bike but I chalked it up to running extremely lean due to the sorry state that the carbs were in.

Does anyone have any thoughts to why it will run high like this? When the bike is cold it will start and then the rpms will start increasing after 5 seconds and just climb. I played with the idle adjustment screw (at the back of the carbs) and it didn't seem to have much of an effect (which direction would turn down the idle?).

As I mentioned, I am not a mechanic at all..this is my first attempt at my own repairs...I pulled and put back the carbs myself...is there something I could have done wrong? Is there something I could check?

Sorry for the "book"...I look forward to reading any replies.

[Pat Kelly]

Look for simple solutions 1st. Is the throttle cable (housing) sitting correctly in the holder?

[trapper_canada]

When I re-attached the throttle cable to the carbs it was a "tad" tight....I believe it lifted the throttle (on the carbs) about 2 mm... so in effect it would be like adding a bit of throttle (if its that sensitive) but not enough to account for the high RPMs...it currently sounds like you are giving it full throttle!

[MartyA]

Hey Trapper-
I would search for all the carb tips here on the site, then do all the ones that don't involve running the engine. Do you have your own manual? Was the bike sitting for long? Is the choke out? It is not really a choke, but an 'enrichening' circuit for cold starts. Are the slides all down, not hanging? Lots of things to check.

What did the Yammie dealer do? Did he test anything after he found the *one* problem? Did he balance them? Telling you that the "...others [idle mixture screw tips] should be replaced for efficiency..." tells me he may have replaced one jet and did not matched it or did not check it to the other 3? Something sounds weird there. But I am naturally suspicious of dealers.

As to the throttle 2mm, that is not much, but adjust it anyway. An engine can rev good and high with a little throttle in neutral, as opposed to opening the throttle in gear under load.

[Ken Talbot]

When the throttle cable is properly installed and seated, there should be just the slightest amount of slack in the cable before the butterflies start to open. If yours is that tight, start by backing off the cable slack adjuster. You'll find it just before the cable goes into the twist grip. Then you might have more luck getting the idle screw to adjust properly.

[sksxs1100]

the very first time i EVER worked on my carbs... I had the same problem.. it was because the carbs were not synced...

[trapper_canada]

Originally posted by sksxs1100
the very first time i EVER worked on my carbs... I had the same problem.. it was because the carbs were not synced...

The carbs were pre-synced (by the shop) before I put them on. I am wondering how I could sync the carbs with the engine running that high?

When the engine is dead cold it will start and idle at 1000 (as seen on the tach) rpms for about 7 seconds...then go to 1500 for another 5 seconds...then it goes to 2000 for 5 seconds then within the next 4 seconds will climb FAST until I shut the bike off (usually at 4500rpms) cause the RPMS keeps climbing.

There has to be something "bigger" thatt needs to be done before I can sync the carbs.

Just to confirm...the main idle adjustment skrew (at the back of the carbs) gets turned COUNTER-clockwise to DECREASE the idle right? And the 4 idle adjustment skrews on the carbs would get turned COUNTER-clockwise to richen the mixture (combatting the lean symptoms I am getting)???

The dealer put the idle adjustment skrews at what he called "stock" settings... I have turned all 4 skrews 2 1/2 turns out (counter-clockwise). I don't know if it helped all that much...how far out can they go?

The other thing that I checked (from reading prev posts) is the boots going from the heads to the carb. They are pretty badly cracked from the outside but when I had the carbs off I felt the insides of the boots and it looked like none of the cracks went through.

Any other thoughts would be GREATLY appreciated! One things for sure...I have learned more about motorcycle carbs/engine than I thought I ever would! But even with all the pain ... I am actually having alot of fun...much to the chagrin of my wife who has noticed (and commented) on the dramatic decrease in my chores

[Meista007]

I know it's a dumb question, but is your choke out?

[pgg]

An even dumber question - have all carb slides got springs on them?

[trapper_canada]

With me there is DEFINITELY no dumb question....the choke is in....I am PRETTY sure that there are springs on the carb slides...but I will re-confirm.

[Snow]

Out of curiosity, did the shop also replace the pilot jets?

[trapper_canada]

Originally posted by Snow
Out of curiosity, did the shop also replace the pilot jets?

No....essentially they just took it apart and put it through their "cleaning routine" for a couple days.

[skids]

I wonder if they use the later model specs for the float heights? The smaller distance (upside down when measuring) for the later carbs would mean excessive fuel levels for the 79 models.

No....essentially they just took it apart and put it through their "cleaning routine" for a couple days.

[jimg1au]

high engine rpm

hi
i had the same trouble when i was first learning to tune my xs1100s.you would start of ok and after a few mins the rpm would rise. then rise agian after a few more mins.i was trying to sync my carbs.this had me stumpped.i rang my older brother who is a brit bike expert and a dam good tunner as well.he lives 400klm away and said to me
1 are you tuning the bike in the garage. i said yes.
2 have you a fan blowwing cold air onto the motor.i said no.
3 go ang get a fan to blow cool air on the motor. and if this dosent work ring me back. i didnt ring him back. put the old house fan in frount of the motor,ran like a dream after i synced the carbs.
hope this is some help
jim garvey
2x XS1100RH
1x xs1100H

[trapper_canada]

EUREKA

Well it turns out Pat and Ken were right. The throttle cable was too tight. I knew it was snug but I didn't think it was opening the throttle on the carbs.

But after re-reading this thread I went back and unhooked the throttle cable from the carbs....and the bike did not take off on me...idled consistently for a good 10 minutes.

So..that leaves me with a bit of a problem. The cable slack adjuster thingy won't turn for me. I think because of age. The little nut will turn a few times to loosen from the main adjuster skrew but I can not get it to turn...I used WD40 but no luck.

I checked on the carbs ant the throttle cable housing was bent up a bit...so I bent it down a tad and it gave me a bit more room...but not enough.

Any ideas?