Some probs with my MM 700 '01

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yamaha_nisse

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Mar 20, 2008
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69
Age
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Hi guys..

Just put together my rebuild MM engine. New pistons, new crank etc.
Have Bender Trippel pipes on it.
Also put Boost-bottle, V-force 3, reedspacers. I had to use coils from a sx 700 '98 (the ones on the airbox).

So.. I pulled and pulled and pulled. nothing happend stone dead. Checked spark looks fine, checked comp. fine!
Poured some gas into the combust chamber and wooam, it fired for a sec then stone dead....

Removed the boost bottle and changed the carbs (stock jetting accept the MJ = 150)

Pulled forever and then it started, but ran extremely bad at low RPM up to 5500... Then it ran as usaul..
I thinking of to lean mixture..

Then I ran it warm.. Stoped waited for it to cool down. And IT wouldn't start..
Pulled maybe 20-30 times and poured some gas in to the cylinder. Then it fired up.
Ran as last time, but if u held it at say 4000RPM it could "miss" to ignite for a sec then start to fire again.
Turned it of.. Started again then it only Ran for one sec. then died, start at first pull but only ran for 1sec.. Didn't mather if u held full throttle or not..

I know it runs low on idle-->1/4 throttle.. But Why does it miss to ignite and it doesn't sound like a tripple a low RPM!

Can it have to do with I using some old COILS?

Thx Rasmus
 

might be different coils... 98 SX uses a wasted spark ignition, firing all three coils simultaneously with coils connected in series... 01 MM uses three separate coils connected in parralell to the CDI firing one coil separate from the others... check schematics for each...

look at the back of each manual for schematics:

http://www.yamaha-motor.com/sport/service/viewmanuals/viewmanuals.aspx?ls=sport
 
TJ500 said:
might be different coils... 98 SX uses a wasted spark ignition, firing all three coils simultaneously with coils connected in series... 01 MM uses three separate coils connected in parralell to the CDI firing one coil separate from the others... check schematics for each...

look at the back of each manual for schematics:

http://www.yamaha-motor.com/sport/service/viewmanuals/viewmanuals.aspx?ls=sport
Click to expand...


Thx..
Got ahold of the "workshop" manual for both ignition systems...

Seems to be a big difference between them.. Have to change, also I would try bypass lightning system..

Come back if it won't work!

And oh, this is the first sled I changed pistons in.. Are they hard started when they are changed?

//Rasmsu
 
mine is a bear to start after jet changes. it takes the fuel pump a bit to pick up. I get around it by using propane in the airbox.
 
high country said:
mine is a bear to start after jet changes. it takes the fuel pump a bit to pick up. I get around it by using propane in the airbox.
Click to expand...

Yepp, I don't use propan but a similar gas to help start my motor.. After I get my stuff I top up the fuel also!
 
I had trouble starting my wifes MM when it was real cold. It started fine loading on the trailer, then it wouldn't start to take it off. It was real cold (-6f). Ended up being a little frozen water in the fuel system. I got it in the garage, warmed it up, and it started right away. I put fuel system antifreeze in and no more problems.
 
I have had similar problems in the past. I carry heat packs with me. Open one up get it hot and lay it on the fuel pump for a little bit. Has work for me everytime. If you have electricity available use a hair dryer. Soc
 
Maybe got to mention that it's total rebuild engine, and the problem has been from the first start..
Even if I let it stand in a heated garage for a day or two!
 
Solved it....

Switched carbs, jetted them:

MJ 150 strahigh over
PJ 52.5
Fuel screw 1½ turns out

And put on 3D coils.. Fired up an ran perfect...

Ran it 4-5 miles before I hit a rock.. Radius rods and steering thrashed :o| :o|
 
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