- Posts: 4
- Thank you received: 0
Engine will not accelerate
- Old80LTD
- Topic Author
- Offline
- User
New spark plugs
Checked the coils
Set and cleaned the points
Set the timing
Checked the compression – 120 per hole
Set the cam timing – someone touched it before me and had it 1 tooth off.
Checked the valve lash
Cleaned the carbs – twice – all passages and jets are clear
So here is what it does wrong, once it is warmed up it will idle like a sewing machine, but when you try to slowly or fast rev the engine, and it starts to go above a fast idle into the midrange it misses and starves out, it looks as if the slides are not lifting fast enough. I did check the slide valve diaphragms and there are no holes and they seem to be pliable. Someone said it needs to have the air box on it to run correctly, maybe under a load but I have never seen this just sitting there running in the garage! So the other day I looked at it again and I did an experiment with the Keihin carbs that are on it, (I would rather have good set of Mikuni carbs!) trying to rule out at least something in the slide valve area of the carb. So after it was warmed up it did the same thing when you would try to rev the engine a bit, it was running without the air box, so I covered the air passages, on both carbs, on the intake side of the carb that leads to the underside of the slide valve diaphragm, then tried to rev the engine again, issue was gone!! The engine accelerated like it should!!! So what does that mean?? Are there any Keihin CV carb experts that could maybe give me an idea what might be the issue? Here is a picture of the passages I covered which make it run correctly. Any input would be greatly appreciated!!
Attachment Carb.jpg not found
Please Log in or Create an account to join the conversation.
- 650ed
- Offline
- User
- Posts: 15344
- Thank you received: 2829
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
Please Log in or Create an account to join the conversation.
- Old80LTD
- Topic Author
- Offline
- User
- Posts: 4
- Thank you received: 0
Please Log in or Create an account to join the conversation.
- Nessism
- Offline
- Sustaining Member
- Posts: 7528
- Thank you received: 2840
Oh, and when you "cleaned" the carbs did that include fully breaking them down, soaking all the parts in car dip, verifying the small passages such as those in the pilot jets and pilot feed passages are open? If not, your carbs are not truly clean.
Please Log in or Create an account to join the conversation.
- SWest
- Offline
- Sustaining Member
- 10 22 2014
- Posts: 23008
- Thank you received: 2755
Steve
Please Log in or Create an account to join the conversation.
- Nessism
- Offline
- Sustaining Member
- Posts: 7528
- Thank you received: 2840
swest wrote: I don't see any needles in the slides.
Steve
Steve's got the eagle eye. :ohmy: Needles?
EDIT: nevermind. Just saw the response that the photo is not the carbs in question.
Please Log in or Create an account to join the conversation.
- Old80LTD
- Topic Author
- Offline
- User
- Posts: 4
- Thank you received: 0
Please Log in or Create an account to join the conversation.
- SWest
- Offline
- Sustaining Member
- 10 22 2014
- Posts: 23008
- Thank you received: 2755
Steve
Please Log in or Create an account to join the conversation.
- EricTheLeg
- Offline
- User
- Posts: 36
- Thank you received: 0
As I work through mine, if I come across a magic bullet fix, I'll let you know.
1983 Kawasaki KZ440 LTD D/Belt - the road bike
1986 Husqvarna WR400 - the dirt bike
1985 Husqvarna WRX400 - The Project bike
Please Log in or Create an account to join the conversation.
- Old80LTD
- Topic Author
- Offline
- User
- Posts: 4
- Thank you received: 0
I did do the thumb test and the slides drop much slower than without anything covering the port, so here is what I was going to do, I am going to re-clean the carbs with an ultrasonic cleaner we have and then try again, if it still does not correct the issue I think that the diaphragms might be no pliable enough and might need new ones. Has anyone replaced these? What is a good source for them?
Another question is does anyone know of a good solution to use with the ultrasonic cleaner? One guy I know says that simple green 50% with water will clean pretty much any carb!
Please Log in or Create an account to join the conversation.
- Nerdy
- Offline
- Sustaining Member
- Posts: 1057
- Thank you received: 413
Old80LTD wrote: Another question is does anyone know of a good solution to use with the ultrasonic cleaner? One guy I know says that simple green 50% with water will clean pretty much any carb!
The green Simple Green (bear with me) can be problematic on some types of metal. (Aluminum comes to mind.)
There is however a purple Simple Green you might try: it is labeled as safe for all metal surfaces. Home Depot carries it but it should be available elsewhere too.
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R
Please Log in or Create an account to join the conversation.
- Nessism
- Offline
- Sustaining Member
- Posts: 7528
- Thank you received: 2840
Please Log in or Create an account to join the conversation.