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CCM 604 poor running
Topic Started: Jan 19 2018, 07:23 AM (326 Views)
Russell Jupp
Commoner
[ * ]
Morning all,
not sure if I'm posting in the proper place....?

Customer has 2003 ccm 604sm
Has a viper can fitted.

Starts fine, idles fine but has a 'flat spot' at 3/4 ish throttle openings.
Its been to a few techie mechanics, but no one seems to be able to cure it.

Its running a dellorto carburettor, has had new jets, and needle, but still has this flat spot.
It has been suggested a carburettor upgrade to a Mikuni may sort this?
Just wondering if any techie purple here can offer any help?
thanks
Russ
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Monty
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Charlie Big Banana's
[ *  *  *  *  *  *  *  *  *  * ]
welcome along

Is the mechanical bits OK, belt timing (had a few that are a tooth out due to lower pulley fitted incorrectly)
compression, should be 150 plus.

what jets? mains with a open can 185

Most importantly is the float height, 17mm, if wrong will give symtoms like you have

Idealy a dyno run to see whats what
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Russell Jupp
Commoner
[ * ]
Thanks for the welcome Monty.
Mechanically its excellent, new plug, coil, carb jets, needle etc.
I checked the valve clearances a couple weeks ago, they were spot on.
Low miles.
I think I'll remove the carb, check the jets and float height. Presumably float height is checked 'on the bench'?
Thanks again,
Russ
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Monty
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Charlie Big Banana's
[ *  *  *  *  *  *  *  *  *  * ]
Have a read here, got a pic of how to do it
http://forum.ccmmad.co.uk/topic/7375887/1/

also some carb info for you
Carb info I found previously from this forum

Dellorto
Gasket set: 52544-77
Needle: K32
Needle jet/atomiser: 268DR
Float needle valve: for the 604 is a 300.
Main jet: 175 standard for 604, 185 for a 636? Fit 185 for aftermarket cans on a 604.
Idle/Pilot jet: The CCM factory said that they fitted a 32 idle jet purely to get it through emissions, but to get the thing to run right it needs a 40 idle jet.
Choke jet: If it is a 60 put a 47 in. It will start and idle on choke then whilst you put your gear on etc., something they never do standard.
Settings on the Rotax carb are absolutely critical especially the float height which should be 17mm.
Put the aftermarket can on, up jet to 185 main and drill the airbox, try needle second richest, one groove up from the pointy end, set idle mix 1.5 - 2.5 turns out
On a 40 pilot 2.5 turns out should be enough, but if 3.5 works then it’s all good!
Be sure that the slide is sitting home (closed) with slack in the cable before adjusting the idle speed.
If the slide is raised on the cable to achieve tickover the idle circuit is bypassed, this will make it a pig to start and you will never get the idle mixture correct.
Worth checking the throttle cable for free play when the idle screw is wound all the way out.
1. Set idle slightly high (so it won’t stall, with bike fully warmed up)
2. Wind mixture screw in till engine starts to hunt/ go fluffy
3. Wind screw out, counting the half turns as you go, till engine again starts to hunt/go fluffy.
4. Set the screw half way, i.e. if you counted 3 complete turns out (between fluffy in and fluffy out) screw in 1˝ turns, that then will be your optimum setting for the mixture screw.

more info on site, if you use the search function and type in "rotax float height" you will find loads on carb fixes
Edited by Monty, Jan 19 2018, 03:58 PM.
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Russell Jupp
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Thank you Monty….
this is great info!I'll let you know how i get on.

BTW, do these carbs wear out, or are they prone to poor running, or are they bullet proof?
Cheers,
Russ

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Monty
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Charlie Big Banana's
[ *  *  *  *  *  *  *  *  *  * ]
Not known any to wear out, the slides can, but that would be obvious, A good ultra sonic clean does wonders, Plus these bike are recomended to run on 98 oct not 95.

If set up right, even a 15 year old carb will work perfectly
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Russell Jupp
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Thanks!
Whats the science behind drilling the airbox?
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motomaniac
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King
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More air in... they need to breath...
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lahauteur
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Rider
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Has anyone done anything to work out what size the extra holes should be? I have seen pics with a few 1" holes and others with the whole side cut out. Any thoughts?
2001 Rotax 640e Supermoto, 1998 350 Bullet and 2000 SV650S
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Roadster604
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Psycho Dad
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If you look at the pictures of the R30 race bikes they cut the sides out as to create a completley open air box, then jet to suit, but if off road not a good idea!
keep the faith
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Russell Jupp
Commoner
[ * ]
Hmm..been thinking about this bike today...I dont think it has an airbox at all. To be honest I didnt take a lot of notice, but I do remember it seemed to have a huge cylindrical shaped foam filter strapped to the carb.
Its in my workshop on Thursday, so I'll know then.
Russ
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motomaniac
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King
[ *  *  *  *  *  *  *  *  * ]
I originally cut 3x1” holes in one side and cut the whole other side off, just masked it over with some mesh. Now i just run a k&n filter and no airbox at all.
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Russell Jupp
Commoner
[ * ]
Monty
Jan 19 2018, 03:50 PM
Have a read here, got a pic of how to do it
http://forum.ccmmad.co.uk/topic/7375887/1/

also some carb info for you
Carb info I found previously from this forum

Dellorto
Gasket set: 52544-77
Needle: K32
Needle jet/atomiser: 268DR
Float needle valve: for the 604 is a 300.
Main jet: 175 standard for 604, 185 for a 636? Fit 185 for aftermarket cans on a 604.
Idle/Pilot jet: The CCM factory said that they fitted a 32 idle jet purely to get it through emissions, but to get the thing to run right it needs a 40 idle jet.
Choke jet: If it is a 60 put a 47 in. It will start and idle on choke then whilst you put your gear on etc., something they never do standard.
Settings on the Rotax carb are absolutely critical especially the float height which should be 17mm.
Put the aftermarket can on, up jet to 185 main and drill the airbox, try needle second richest, one groove up from the pointy end, set idle mix 1.5 - 2.5 turns out
On a 40 pilot 2.5 turns out should be enough, but if 3.5 works then it’s all good!
Be sure that the slide is sitting home (closed) with slack in the cable before adjusting the idle speed.
If the slide is raised on the cable to achieve tickover the idle circuit is bypassed, this will make it a pig to start and you will never get the idle mixture correct.
Worth checking the throttle cable for free play when the idle screw is wound all the way out.
1. Set idle slightly high (so it won’t stall, with bike fully warmed up)
2. Wind mixture screw in till engine starts to hunt/ go fluffy
3. Wind screw out, counting the half turns as you go, till engine again starts to hunt/go fluffy.
4. Set the screw half way, i.e. if you counted 3 complete turns out (between fluffy in and fluffy out) screw in 1˝ turns, that then will be your optimum setting for the mixture screw.

more info on site, if you use the search function and type in "rotax float height" you will find loads on carb fixes
Hi Monty,
OK, got the beast in bits….
Firstly it has a drilled air box, with no lid. A large foam filter sits inside.
Main jet: 200
Pilot jet: 42
Choke jet: 55
Needle valve: 300
Needle jet: 268DR
Needle: K32

So everything seems std, except the main jet?
Just checking the float height.
Thanks
Russ
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Monty
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Charlie Big Banana's
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I would try a 185 main jet, A 200 is a tad large unless like motomaniac you have a big bore and flowed head, You may even find that the foam filter could be colapsing with the vacuum, So some have made a cage out of wire and fitted inside. or buy a K&N.
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Russell Jupp
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Monty
Jan 26 2018, 04:10 PM
I would try a 185 main jet, A 200 is a tad large unless like motomaniac you have a big bore and flowed head, You may even find that the foam filter could be colapsing with the vacuum, So some have made a cage out of wire and fitted inside. or buy a K&N.
Yep, will do.
However, upon checking the float height, unless I'm wildly mistaken (and blind) it appeared to be around 21mm.
This is with the carb stood on its intake end, flat surface, floats at rest.
Ive bent the tab a little, it now appears to be around 18mm
I'll stick it back together, and try it.
Cheers
Russ
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Monty
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Charlie Big Banana's
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if you used the link in post #4, there is a diagram of how to check it, but you seem to have sussed it, At 21mm there would hardly be any fuel in the bowl which will cause problems.
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Russell Jupp
Commoner
[ * ]
Hi Monty,
customer has tested bike this weekend, and is really pleased. It seems to be almost perfect.
However, he'd like me to fit the correct 185 main jet.
Do you by any chance, have any info on where to buy a jet, and jet thread size etc etc?
Thanks for all your help,
Russ
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stevo604
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God
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Russell Jupp
Feb 5 2018, 08:37 AM
Hi Monty,
customer has tested bike this weekend, and is really pleased. It seems to be almost perfect.
However, he'd like me to fit the correct 185 main jet.
Do you by any chance, have any info on where to buy a jet, and jet thread size etc etc?
Thanks for all your help,
Russ
this were I get all my bits for carb

Eurocarb Ltd
Unit 2 Horseshoe Park Pangbourne
Reading RG8 7JW United Kingdom
Phone: +44 118 984 2811
Fax: +44 118 984 1709
Open Monday - Friday, 9am - 5pm
Email: sales@dellorto.co.uk
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motomaniac
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King
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As said, foam filter can collapse under load, so a k&n would be a worthwhile addition too, especially with the drilled box and open can...
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Russell Jupp
Commoner
[ * ]
Hello, thanks for this info. The can does have a DB killer in the end of it.
But, I think I'll replace the filter for an alternative.
Sorry to be a pain, but again I don't suppose you'd have info on where to buy a K&N?
I had a look at EUROCARB, they seem to sell filters, but not K&N.
Found one on Ebay, but just want to make sure I get the correct one!!
Cheers
Russ
Edited by Russell Jupp, Feb 5 2018, 04:07 PM.
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