MT500 upgrading into a MT604

[Roy W]

This 604 is driving me around the twist. Starts and ticks over fine. Tried riding it and that's when the fun starts won't pull feels like fuel starvation or its restricted.
Changed the 40 dellorto for a new mikuni no change
checked timing
change the plug no change
changed the cdi no change
change the coil no change
Removed the ccm silencer pulls like a train over 70 on a side street
Fitted original stainless 500 silencer back to restrictive
bashed baffles open no change
I'm guessing the exhaust is the problem but don't know what to try next Anyone got any ideas.
Cheers Gary.

I had similar problems with my 640. Just persevere, it is probably carburation issues. I solved most of mine by lifting the needle a notch in the dellorto PHM40 . Jets were by trial and error.

Still have minor issues at 1/4 throttle with hesitation.

I use a CCM end can on the 640 with no issues. I used a Supertrapp too, but it was too bloody loud.

I nearly gave up on mine several times but am glad I didn't now.

Good luck

[Yoof]

Just fuel inject it

[worz]

Spent another day in the garage double checking everything twice, electrics, timing, value clearances. The only thing I have found wrong was the breather pipe from the bottom of the engine up to the air box ( same as the 350 ) was blocked with oil. Cleared the blockage and it has made a difference. Put the CCM silencer back on still restricted ended up smashing a 2" hole in the baffle ( Manchester hammer strikes again ) Which has made a vast improvement now able to ride the bloody thing. Can now ride it sedately through traffic 25/35 MPH but give it a handful it starts to sputter for a few seconds then pops a wheelie in second gear then its off Stopping on drum brakes is fun as well . I will have to start tweeking the carb now see if I can improve it some more. Also have to sort out the oil leaks its like a bloody sieve.

[MT Pocket]

Sounds like it needs a dyno jet session.

[ellrider]

Sounds like it needs a dyno jet session.

And a disc brake front end.

[Yoof]

Is the pumper working?

[MT Pocket]

PHM = no pumper
My 604 donor didn't have one

[worz]

dyno session next I think cant do it any harm. The dellorto was in a poor condition lots of parts were seized up so I have fitted a mikuni same as Andys 604. I'm going to try adjusting the needle next what changes do you get moving it up or down.
Cheers Gary.

[ellrider]

The needle(and needle jet) affects carburation between 1/4 - 3/4 throttle setting, lifting the needle makes it richer, lowering the needle makes it weaker.

Some find it confusing but raising the needle means placing the clip in a lower groove and ie lowering the needle means placing the clip in an upper groove.

If your problem is between these throttle settings and you're not sure which way to go try one way and if it gets worse move it the other way.

[MT Pocket]

Drum brakes on a 604 eeeeek - what happened to your disc brake mod? Or is that on a different bike.