lt250 lt500 motor swap
#21
11-20-2005, 04:44 PM
#22
11-22-2005, 03:09 PM
lt250 lt500 motor swap
I've been waiting for this post cause i need help. Picked up a real nice lt250 w/ zilla motor off a guy we hillclimb with for short money. Need some tuning/ carb adjustment advice.
Here's what i know about the motor- 14mm extended connecting rod, cr500 piston so skirts clear rod, has a spacer block (maybe 10mm?) between head and cases, lectron 44 mm carb, pipe looks just like the ones pictures on post above except it is not as smooth, maybe half as many pieces.
I am breaking the motor down soon to fix a jammed 1st/n/2nd gear fork, but bike really excites me... ran 5.4 in 300ft sand drag with 270lb me on it, no paddles, no wheelie bar, lousy trans... on 104 octane (most ran alcohol or 110)
Need help with the carb/plug/ignition selection. This bike is very hard to start, pull starts right up, but kicking it takes very hard long kicks and a lot of them... is this to be expected?
Everyone else w/ zillas at the sand drags ran alcohol so it was hard to compare them... My banshees and lt250r start right up... is there an ignition upgrade i need? ran a br8es plug? Do I have the right carb? Any tricks for starting these bikes with this carb?
Thanks in advance. I'll post some pics.
Here's what i know about the motor- 14mm extended connecting rod, cr500 piston so skirts clear rod, has a spacer block (maybe 10mm?) between head and cases, lectron 44 mm carb, pipe looks just like the ones pictures on post above except it is not as smooth, maybe half as many pieces.
I am breaking the motor down soon to fix a jammed 1st/n/2nd gear fork, but bike really excites me... ran 5.4 in 300ft sand drag with 270lb me on it, no paddles, no wheelie bar, lousy trans... on 104 octane (most ran alcohol or 110)
Need help with the carb/plug/ignition selection. This bike is very hard to start, pull starts right up, but kicking it takes very hard long kicks and a lot of them... is this to be expected?
Everyone else w/ zillas at the sand drags ran alcohol so it was hard to compare them... My banshees and lt250r start right up... is there an ignition upgrade i need? ran a br8es plug? Do I have the right carb? Any tricks for starting these bikes with this carb?
Thanks in advance. I'll post some pics.
#25
11-23-2005, 08:05 PM
lt250 lt500 motor swap
Hi,
Where do I start?
5.4s.......... I wouldn't get to happy about that.......... we ran 4.9s on a stock chassis, stock cyl, stock sleeve 87 LT250.
Well..................................... First off a "long rod/CR500 piston" motor is f-ed up from the beginning. It has a HUGE "freeport" condition (the exhaust port is open under the piston as the piston gets to TDC.................most knuckleheads never check this out/understand when building a "super-duper" longrod motor.....I was once one of those knuckleheads way back in the day)
This allows the exhaust gas return pulse to "contaminate" the A/F charge in the cases.
Now for some good news............ if you run the bike on methanol as a drag only set-up the freeport doesn't hurt the motor as much at higher RPM's and it could run pretty decent w/out welding up 2 CR500 pistons to fix the condition.
The longrod is a good idea, but you need a piston to match............there are none available that I know of other than my custom 650 Roidzilla pistons or a modded KTM 550 piston.
I didn't see the pic of the pipe, but I would guess it's a Trinity LT500 in-frame drag pipe...............not EVEN CLOSE to how my pipes run.
I think if you built a wheelie bar, switched to methanol and got a decent pipe the bike would run pretty hard and I'm sure it would go high 4s w/no problem.
Overall, it looks good and I'm sure it's a lot of fun.
$.02
RK
Where do I start?
5.4s.......... I wouldn't get to happy about that.......... we ran 4.9s on a stock chassis, stock cyl, stock sleeve 87 LT250.
Well..................................... First off a "long rod/CR500 piston" motor is f-ed up from the beginning. It has a HUGE "freeport" condition (the exhaust port is open under the piston as the piston gets to TDC.................most knuckleheads never check this out/understand when building a "super-duper" longrod motor.....I was once one of those knuckleheads way back in the day)
This allows the exhaust gas return pulse to "contaminate" the A/F charge in the cases.
Now for some good news............ if you run the bike on methanol as a drag only set-up the freeport doesn't hurt the motor as much at higher RPM's and it could run pretty decent w/out welding up 2 CR500 pistons to fix the condition.
The longrod is a good idea, but you need a piston to match............there are none available that I know of other than my custom 650 Roidzilla pistons or a modded KTM 550 piston.
I didn't see the pic of the pipe, but I would guess it's a Trinity LT500 in-frame drag pipe...............not EVEN CLOSE to how my pipes run.
I think if you built a wheelie bar, switched to methanol and got a decent pipe the bike would run pretty hard and I'm sure it would go high 4s w/no problem.
Overall, it looks good and I'm sure it's a lot of fun.
$.02
RK
#27
11-25-2005, 03:01 PM
#29
11-29-2005, 11:43 AM
lt250 lt500 motor swap
Hi,
I am very familiar w/this bike set-up as most of you already know, having done over a dozen of them.
Currently, I am building another hybrid duner for myself as my son is getting my "ol reliable" that has been freshened up a bit.
I will be building a very limited number of pipes, chromemoly lightweight a-arms and swingarms for this swap.
W/out a decent pipe and suspension the "hybrid LT250/500R" has very limited capabilities.
My favorite set-up is plus 4" swingarm and 3" wider front a-arms. This set-up roosts thru the dunes just awesome and allows you to use the full capabilities of a built LT500 motor w/out being too long to jump. The full throttle powerslides and 4th and 5th gear power wheelies will "ruin" you for ever riding any other 4 wheel duner forever. I get on an LT500 after riding my bike and immediately i think "man, this thing is a heavy pig".
We build the a-arms to use the YFZ450 front shocks and will yield about 9.5" of travel in the front.
The 4" over swingarm will yield about 9.5" of travel in the rear and can use a stock rear shocked that is revalved and resprung.
My "new" bike uses a YFZ450 rear shock in a no-link configuration for about 10" of travel. It requires some serious shock mount fabrication and a matching swingarm.
Any of you doing this swap that need suspension advice/help just send me a PM or post.
$.02
RK
I am very familiar w/this bike set-up as most of you already know, having done over a dozen of them.
Currently, I am building another hybrid duner for myself as my son is getting my "ol reliable" that has been freshened up a bit.
I will be building a very limited number of pipes, chromemoly lightweight a-arms and swingarms for this swap.
W/out a decent pipe and suspension the "hybrid LT250/500R" has very limited capabilities.
My favorite set-up is plus 4" swingarm and 3" wider front a-arms. This set-up roosts thru the dunes just awesome and allows you to use the full capabilities of a built LT500 motor w/out being too long to jump. The full throttle powerslides and 4th and 5th gear power wheelies will "ruin" you for ever riding any other 4 wheel duner forever. I get on an LT500 after riding my bike and immediately i think "man, this thing is a heavy pig".
We build the a-arms to use the YFZ450 front shocks and will yield about 9.5" of travel in the front.
The 4" over swingarm will yield about 9.5" of travel in the rear and can use a stock rear shocked that is revalved and resprung.
My "new" bike uses a YFZ450 rear shock in a no-link configuration for about 10" of travel. It requires some serious shock mount fabrication and a matching swingarm.
Any of you doing this swap that need suspension advice/help just send me a PM or post.
$.02
RK
#30
11-29-2005, 11:51 AM
lt250 lt500 motor swap
RK, Thanks for the info, I truely appreciate it.
BTW on a side note, I'm very happy with the 5.4's given that it was the second time ive dragged raced, my weight, the bikes condition- (not built for drag racing), and in comparison to what is was running it did good. A full drag 500 suzuki on alcohol was only running 4.6's with a wheelie bar- which must be worth 3/4 of a second at least. I think my bike would easily run mid 4's with a smaller rider, different tires, and a wheelie bar as is. There was nothing even close to being in the 4's out of a stock 250... The closest was a 5.1 out of a honda 250 with the 370 kit, and that was snow tires and a very good rider. Thats neither here nor there- my bike was either wheelieing or roosting the whole way down the track and it pulled strong which is what I care about.
Anyways, I'm not trying to build a drag bike, a want a dunes/gravel pit bike thats fast, runs consistent and that I can run amatuer hillclimbs on. I plan on a trip across the country to ride glamis, maybe hit michigan, and before I even start planning, I want this bike to be running proper.
I would like to switch to alcohol so that it will run cooler, but dont want to because you cant run an alcohol setup on the hillclimbs. I also know absolutely nothing about the conversion. Any links, quick resources?
I am breaking the motor down very soon to fix a tranny fork problem it has and would like to know more about the pistons you speak of... would this make it run better and start easier or just have it running faster? What kind of money am I taking to have one of these roidzilla or ktm pistons fabbed?
Thanks for the input
BTW on a side note, I'm very happy with the 5.4's given that it was the second time ive dragged raced, my weight, the bikes condition- (not built for drag racing), and in comparison to what is was running it did good. A full drag 500 suzuki on alcohol was only running 4.6's with a wheelie bar- which must be worth 3/4 of a second at least. I think my bike would easily run mid 4's with a smaller rider, different tires, and a wheelie bar as is. There was nothing even close to being in the 4's out of a stock 250... The closest was a 5.1 out of a honda 250 with the 370 kit, and that was snow tires and a very good rider. Thats neither here nor there- my bike was either wheelieing or roosting the whole way down the track and it pulled strong which is what I care about.
Anyways, I'm not trying to build a drag bike, a want a dunes/gravel pit bike thats fast, runs consistent and that I can run amatuer hillclimbs on. I plan on a trip across the country to ride glamis, maybe hit michigan, and before I even start planning, I want this bike to be running proper.
I would like to switch to alcohol so that it will run cooler, but dont want to because you cant run an alcohol setup on the hillclimbs. I also know absolutely nothing about the conversion. Any links, quick resources?
I am breaking the motor down very soon to fix a tranny fork problem it has and would like to know more about the pistons you speak of... would this make it run better and start easier or just have it running faster? What kind of money am I taking to have one of these roidzilla or ktm pistons fabbed?
Thanks for the input