250 air cooled max temperture cooling methods? - Page 2

ChondaChondaChonda · 08-24-2017, 11:29 PM

Quote:

Originally Posted by crackerjac

Where do you have your needle clip set at? (from the top going down)

Every motor will be a little different... plus I'm at 5000 ft above sea level.

My clip had to be moved down (which pulls the needle up) to get a little richer mixture. I believe it is in the 2nd slit from the bottom, moved from the center slit of 5.

crackerjac · 08-25-2017, 08:11 AM

Quote:

Originally Posted by ChondaChondaChonda

Every motor will be a little different... plus I'm at 5000 ft above sea level.

My clip had to be moved down (which pulls the needle up) to get a little richer mixture. I believe it is in the 2nd slit from the bottom, moved from the center slit of 5.

I'm only 785ft above sea level. I have mine in the middle clip but it might be too rich actually. Holding the throttle about a quarter to half on sitting the motor hesitates and belches with lack of power. I think it's flooding itself out.

pete · 09-06-2017, 05:05 AM

just replace the titainum valves with stainless & a
real piston with a skirt....
Those motors are stressed to the limit... a CRF250
has a detectable power loss after 5 hours use..
They are built to win races not last...
but the CRF dose seem to be the most fagile of
the jap 4T MX bikes..

..

crackerjac · 09-06-2017, 09:13 AM

Around here you'd be paying around $12K easily for a newer bike and racing it or not I'd be pissed if I had to rebuild or replace an engine only after a nominal amount of hours not even beating on the thing. Really bad design on Honda's part. No wonder people flock to KTMs.

Rest of the bike is pretty solid other than the damn Honda wheel spokes that always seem to loosen themselves off no matter what you do.

I picked up my 450X, less motor, for next to nothing because the guy did just that, blew the motor, and he barely rode the thing! Sad, Honda lost another customer there.

b44 · 09-09-2017, 02:55 AM

Yeah just can't justify that kind of coin & rebuilds considering I'm no racer, there a bucket loads of crf250r/450 for sale here, wonder why .how does aftermarket cdi go? Is it the racing one with no rev limiter? Did look into that but thought it may shorten engine life, as bike already gets a hard time, if i come across another crf250r clone with a blown engine ill probably build another one,robust ,cheap & reliable.that 450 chasis actually looks slightly larger than the 250,

crackerjac · 09-09-2017, 12:09 PM

The CDI is from Casoli, one of the gold 6 pin units. It has a rev limiter built in, which I prefer to be honest, and is suppose to have an advanced timing curve. Is it better than stock? I believe it does work better although I had to tune the carb differently for it. The stock unit has a nice smooth idle and ok rev up. The Casoli unit causes a bit of light burp and farts at idle but the ramp up response from idle to full throttle is insane! It did actually wake up the motor if you have a few mods like we do. Only my opinion though.

The 450X (not R) chassis is really nice to work with. No cutting to fit these motors. It is different from all the rest of the bike frames in the CRF lineup and is obviously a bit larger due to the stock 450X having electric start etc. which makes these conversions so nice. The Zong 250 motors fit right in you'd think it was design for it. The main front mount lines up perfect with the top front motor mount on the zong with no extra brackets, just spacers for the bolt through. It was easy to weld a few extra tabs for the other motor mounts and for extra assurance I made a bracket setup for the back that allows the swing-arm pivot bolt to act as a support like the stock CRF motors but it really isn't necessary, just extra assurance.

My biggest hurtle was the wiring. I've done electronics all my life and this is extremely basic wiring but the routing of the wires (since it's not the CRF setup) was a bit tricky. Having to over think it so it was still all accessible but safely tucked away in the frame.

Only other thing was a bit if plastic modding to the stock 450X fuel tank. It's over sized from the factory and sits low in the frame which hit the tall head of this air-cooled zong motor. Basically heat with a paint stripper gun and slowly push the bottom bulge inward. A bit of work but turned out nice.

Anyway, I'm rambling.

09-06-2017, 05:05 AM	#3
pete Join Date: Jan 2012 Location: ChCh , NZ Posts: 2,261	just replace the titainum valves with stainless & a real piston with a skirt.... Those motors are stressed to the limit... a CRF250 has a detectable power loss after 5 hours use.. They are built to win races not last... but the CRF dose seem to be the most fagile of the jap 4T MX bikes.. .. __________________ 09 XT660R ... 06 TTR250 ... 80 Montesa H6 125 Enduro... 77 Montesa Cota 348 MRR "Malcom Rathnell Replica"... Current resto projects.. 81 Honda CT110... 80 Kawasaki KL250A1... 11 Husaburg TE125 enduro... "sold" along with another 31... Lifan 125 Pitbike.. "stolen" ... KIWI BIKER FORUM...... http://www.kiwibiker.co.nz/forums/content.php All the best offroad rides in NZ... http://www.remotemoto.com/ E-mail... xtpete1@gmail.com
	0

09-06-2017, 09:13 AM	#4
crackerjac Join Date: Sep 2016 Posts: 103	Around here you'd be paying around $12K easily for a newer bike and racing it or not I'd be pissed if I had to rebuild or replace an engine only after a nominal amount of hours not even beating on the thing. Really bad design on Honda's part. No wonder people flock to KTMs. Rest of the bike is pretty solid other than the damn Honda wheel spokes that always seem to loosen themselves off no matter what you do. I picked up my 450X, less motor, for next to nothing because the guy did just that, blew the motor, and he barely rode the thing! Sad, Honda lost another customer there.
	0

09-09-2017, 02:55 AM	#5
b44 Join Date: Apr 2016 Location: Australia Posts: 89	Yeah just can't justify that kind of coin & rebuilds considering I'm no racer, there a bucket loads of crf250r/450 for sale here, wonder why .how does aftermarket cdi go? Is it the racing one with no rev limiter? Did look into that but thought it may shorten engine life, as bike already gets a hard time, if i come across another crf250r clone with a blown engine ill probably build another one,robust ,cheap & reliable.that 450 chasis actually looks slightly larger than the 250,
	0

09-09-2017, 12:09 PM	#6
crackerjac Join Date: Sep 2016 Posts: 103	The CDI is from Casoli, one of the gold 6 pin units. It has a rev limiter built in, which I prefer to be honest, and is suppose to have an advanced timing curve. Is it better than stock? I believe it does work better although I had to tune the carb differently for it. The stock unit has a nice smooth idle and ok rev up. The Casoli unit causes a bit of light burp and farts at idle but the ramp up response from idle to full throttle is insane! It did actually wake up the motor if you have a few mods like we do. Only my opinion though. The 450X (not R) chassis is really nice to work with. No cutting to fit these motors. It is different from all the rest of the bike frames in the CRF lineup and is obviously a bit larger due to the stock 450X having electric start etc. which makes these conversions so nice. The Zong 250 motors fit right in you'd think it was design for it. The main front mount lines up perfect with the top front motor mount on the zong with no extra brackets, just spacers for the bolt through. It was easy to weld a few extra tabs for the other motor mounts and for extra assurance I made a bracket setup for the back that allows the swing-arm pivot bolt to act as a support like the stock CRF motors but it really isn't necessary, just extra assurance. My biggest hurtle was the wiring. I've done electronics all my life and this is extremely basic wiring but the routing of the wires (since it's not the CRF setup) was a bit tricky. Having to over think it so it was still all accessible but safely tucked away in the frame. Only other thing was a bit if plastic modding to the stock 450X fuel tank. It's over sized from the factory and sits low in the frame which hit the tall head of this air-cooled zong motor. Basically heat with a paint stripper gun and slowly push the bottom bulge inward. A bit of work but turned out nice. Anyway, I'm rambling.
	1