My Dog does not want to go above 100km/h

[Tik]

I'm so sad, only 1700km and today, trying to go above 110km the engine lost power and now is only able to push up to 100. I thought is working only one cylinder and checked the spark plugs, both look clean and the same.
I have to go to service, isn't it?

[Axman]

Hi Tik,

there is definitly something very wrong..

My guess is, that the engine really is working on only one cylinder ( a spark-plug that is not firing correctly is always clean due to unburnt gasoline washing off all debris !)

Try pulling off the spark-plug cable one at a time while the engine is running ( be careful...use isolated plies !!!) the rythm of the engine should then change..if it doesn´t, you´ve found the culprit.

Other than that I´ve got no ideas from so far away other than what you´ve already said yourself : have your bike serviced..

Let us know what they (or you) found out..

Greets from the Axman

[Mick P]

Hi Tik

What's the bike running like up to 110 km ?

If you have checked your spark and it is OK have you checked your fuel it might be worth draining you carburettor's and checking if it is clean.

There is a drain pipe that drain's water/petrol away from the fill cap if it is bent or blocked and there is water around the fill it can let it into the tank it might be worth a check. This is a small pipe you have to move when you lift the tank if its not put back correctly it is easy to kink, its comes out by the side stand.

Hope you fix it soon Mick P

[moppedwolf]

Hi Tik,
what's about the CDI-box?

better go to service

best wishes
Wolf

[Tik]

Thank you all. Since I've started this thread, I did the following: I took out the seat and the battery to see if gasoline is passing through the filter. The filter seemed empty to me but I did not change it's original position, only looking. However gasoline is flowing because I still use the bike.
Now is a lot of a story about the starter choke (I believe this is the name in English). When I was in service for the 1000km check, the guy from service told me that the choke in normal position (engine warm) is downwards not backwards. And indeed, the bike worked better that way, eating as low as 5.1 /100km. The problem is that in the manual is clearly written in two places that normal position is backwards. Can it be that the manual is wrong?
So I used the bike after 1000km with choke downwards, but after some 500km happened what I was telling you in the first post.
Then I tried again with the choke backwards and so the engine had lots of power with throttle pushed but is unstable at low and medium rotations.
This morning I brought the bike again at local Yamaha service, then again after two hours they called me and told me again the choke has to be downwards, the user book is wrong. I drove all day today with everything perfect, engine sounding round, at low speed moving perfectly till, after 100km I'm loosing power again.

All this story sounds silly but I'm still not convinced that the user book is wrong and I'm also reluctant in opening the carburetor to see how is moving inside when that lever is moved down and backwards. After how the engine works (no smoke, round sound) I'm starting to believe those guys but than that means that I have some problem with the gasoline flow.

Thank you all again. I shall look for Mick's suggestion; What is the CDI box?

[Tik]

Answering to Mick's question, what behaviour when I'm losing power: Engine sounds a little bit different, then it has some pushes (inconstant power for same position of throttle, than begins to be constantly low) It happened about twice I've stopped the engine completely for a few seconds than started back and everything was normal for the rest of the trip. While pushing full throttle in N (no gear) engine works aparently normal.

[Mick P]

Hi Tik

sounds like fuel starvation, check all the pipes on the fuel system make sure they have not been bent over stoping the flow of fuel, also check the fuel pump is working ? some times you can here it clicking when you turn on the ignition.

Try draining the carbs but collect the fuel so you can check to see how clean it is. You said you checked the fuel filter did it look clean.

The choke lever or cold start lever should be down and as far forward for normal running and as far back towards the back wheel for cold start, when i use choke it is only on for a minuite or so, THE USER MANUAL HAS BEEN PRINTED WRONG, also the rear spring adjustment setting in some of the user manuals are wrong so check first if you want to change the settings.

I hope you get it sorted soon Regards Mick

[moppedwolf]

Hi Tik,
I dont know the english owner's guide.

My cold start choke situation has to be backwards and when I drive maybe 500 meters I change the choke forwards till it stops (not only down) so it sign a little bit forward to the front cylinder!

Sounds like: change service station


Wolf

[Axman]

Hi Tik,

your problem seems to be a misinterpretation of the choke usage...so, forget the manual.

When the engine is cold ( and only then !) rotate the choke lever all the way back and start the engine. . After the engine catches -starts running- push the lever forward a little bit till the engine runs more or less smoothly, avoiding higher rpm´s .
Then go riding.
When you notice that the engine responds better to throttle input, push the choke lever in all the way to the stop -to the front- !!

If you ride with the choke lever pointing downward, your choke is still partially open and you are flooding the engine with petrol...which too could cause the symptoms you are experiencing. So just remember : engine cold, choke all the way back...engine warm : choke all the way to the front !!

Let us know what happens..

Cheers, Axman

[Tik]

The friendliest forum ever. Thank you all.

[Axman]

Hi Tik,

what about your problem ??

Let us know..

Cheers, Axman

[Paulchen]

Dear Tik,

It seems to be possible that the carburetor "sneezes" itself of the cylinder or gets sneezed of by the cylinder (I'm not sure).
It happened to a member during a club-tour.
The Yamaha-mecanical told us that it happened once in a while and repared the hole thing back in a few minutes, in this case it was the front cylinder.

[Tik]

I'm so busy theese days, in one week we leave for a two week holiday in Crete and I have to finish most of the emergencies before. Nothing new meanwhile, I have a very good friend who was national champion at motocross some years ago and he told me that the one who is taking care of his bikes (he still competes for fun) shall look at it next week. I'm not using it any more, got worse, sounds strange and is not going higher than 70, so I'm back to my car for a while. I'll tell you for sure what was it, but due to busy calendar in this period, I expect some news only on Wednesday or Thursday.

Gruss.

[Axman]

Hi Tik

meanwhile only 70 Kph ?? This doesn´t sound good....not good at all..

But remember : whatever you do (or your friend does) don´t jeopardise your Guarantee-Claim !! Should he find something mechanically wrong don´t be hasty and open the engine !!

I´m really keen on knowing what is wrong with your dog...so, keep us informed

Cheers, and have a nice Holiday

Axman

[Axman]

Hi Tik,

your very special problem kept coming to mind and I remembered something another Bulldog owner postd a while ago...

He had more or less the same problem : the dog would´nt run properly any more.

Here is what happened : Yamaha glues a foam-mat to the underside of the tank - probably for insulation -. A part of this foam came loose, hung down and thus clogged the air-intake-snorkel

With not enough air the engine would´nt rev any more..

Check it..

Cheers

from the Axman