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250r style intake conversion for stock cylinders.


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Ok, heres the plan. Since I am building a new motor I have a spare engine with trashed cylinders to do some mule work with. I have been talking with a guy about a slight redesign on an already well known bridged exhaust big bore sleeve called the viper sleeve. The current design is a very huge bridged exhaust layout, that is definitely geared toward the drag guys. However, we have been working on a way to get a big bore sleeve with the same style bridged monster exhaust just alot lower, but way wider. And adjust transfers accordingly. Then there is a guy I met at a bike show that is converting the actual cylinders of RD350/RZ350 bikes to 250R style intakes. He actually removes the stock intake plenum off the yamaha cylinders and tig welds on the 250R plenum/flange. The bikes he builds are modded stock cylinder 4mils that are pretty notorious for hunting down well set up 4mil kitty cub motors. So, I figure since there is nothing left on my cylinders to bore/hone, I might as well have the prototype sleeves put in (for nothing), then have this guy set up some of the monster 250r plenums. He says he has been making almost 55+ ft lbs. and 100hp on RD cylinders. The cost on the project is the 450 to machine and weld on new intakes. $200 a cylinder, plus $25 per machined flange. I have pix somewhere of the intake. Let me know if you guys want an update on the turn out.

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Ok, heres the plan. Since I am building a new motor I have a spare engine with trashed cylinders to do some mule work with. I have been talking with a guy about a slight redesign on an already well known bridged exhaust big bore sleeve called the viper sleeve. The current design is a very huge bridged exhaust layout, that is definitely geared toward the drag guys. However, we have been working on a way to get a big bore sleeve with the same style bridged monster exhaust just alot lower, but way wider. And adjust transfers accordingly. Then there is a guy I met at a bike show that is converting the actual cylinders of RD350/RZ350 bikes to 250R style intakes. He actually removes the stock intake plenum off the yamaha cylinders and tig welds on the 250R plenum/flange. The bikes he builds are modded stock cylinder 4mils that are pretty notorious for hunting down well set up 4mil kitty cub motors. So, I figure since there is nothing left on my cylinders to bore/hone, I might as well have the prototype sleeves put in (for nothing), then have this guy set up some of the monster 250r plenums. He says he has been making almost 55+ ft lbs. and 100hp on RD cylinders. The cost on the project is the 450 to machine and weld on new intakes. $200 a cylinder, plus $25 per machined flange. I have pix somewhere of the intake. Let me know if you guys want an update on the turn out.

 

Count me in. I'm always interested in custom fabricated stuff. I like it when people think outside the box.

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Ok, heres the plan. Since I am building a new motor I have a spare engine with trashed cylinders to do some mule work with. I have been talking with a guy about a slight redesign on an already well known bridged exhaust big bore sleeve called the viper sleeve. The current design is a very huge bridged exhaust layout, that is definitely geared toward the drag guys. However, we have been working on a way to get a big bore sleeve with the same style bridged monster exhaust just alot lower, but way wider. And adjust transfers accordingly. Then there is a guy I met at a bike show that is converting the actual cylinders of RD350/RZ350 bikes to 250R style intakes. He actually removes the stock intake plenum off the yamaha cylinders and tig welds on the 250R plenum/flange. The bikes he builds are modded stock cylinder 4mils that are pretty notorious for hunting down well set up 4mil kitty cub motors. So, I figure since there is nothing left on my cylinders to bore/hone, I might as well have the prototype sleeves put in (for nothing), then have this guy set up some of the monster 250r plenums. He says he has been making almost 55+ ft lbs. and 100hp on RD cylinders. The cost on the project is the 450 to machine and weld on new intakes. $200 a cylinder, plus $25 per machined flange. I have pix somewhere of the intake. Let me know if you guys want an update on the turn out.

 

Who is the ones who are modding and welding on the intakes? PSI Power?

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so its going to be a sleeved cylinder with a exhaust bridge in the exhaust port?

Yes, but the bridge is there so you can make a huge triangular exhaust port and not worry about the ring catching or snagging the edge of the port and getting damaged. The problem used to be that big bore sleeves would choke off the transfers, but now we are possibly going to try a little thinner liner with nikasil and hog out a little of the casting area around the transfers while the old sleeves are out. Look around for info on the viper sleeve, it used to me exclusive to Lakes Motorsports, but Mike is trying to sell it on a larger scale now.

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if you do wind up doing this and your gonna run wiseco pistons then make sure you follow the install instructions for the 3 lubrication holes that you must drill for exhaust bridge cylinders. its not hard....dont' forget to debur it to make sure you dont screw the sleeve up. Seen 2 bikes run with exhaust bridges and no lube holes......in the end it doesn't wind up too good for the guy payin the bills... haha

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Who is the ones who are modding and welding on the intakes? PSI Power?

Nah, just a guy who works solo out in Cali as a pull barn legend. Really the dude is more in to RZ/RD 350 road & track bikes. He used to do some work for Moto Carrera, and has recently started building TT Banshees and a dune Shee for himself. Any info on the fellas at PSI Power? Phone number or website?

Edited by trickedcarbine
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if you do wind up doing this and your gonna run wiseco pistons then make sure you follow the install instructions for the 3 lubrication holes that you must drill for exhaust bridge cylinders. its not hard....dont' forget to debur it to make sure you dont screw the sleeve up. Seen 2 bikes run with exhaust bridges and no lube holes......in the end it doesn't wind up too good for the guy payin the bills... haha

.

Good info, appreciate it bro. I have only heard of lube holes like that one time, and it was a very long time ago on a big bore hill climb CR500. I will problably be using blaster style weisco pistons in it so there will be a little more work in it now. Better then losing another set of pistons. Any way I can ask you to elaborate on the concept of the procedure and how it really works with out leaking the air/fuel charge off through the front of the piston, or is it just a few pin holes exactley in front of the bridge. I ran some Viper Sleeves before and had no issues. Just wondering how nessacary they are. Also, what about another style of piston, such as WSM?

Edited by trickedcarbine
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post pics of the motors. !!!!!

 

421stocker are capable of around 55ftlbs of tq and 85ish+ hp with a non bridged exhaust and std intake.

 

but i'm curious. the motor would probably need to be pretty big to necesitate r intakes. cubs have proven that. the bridged exhaust is kinda known to crack because of the thinness of the bridge. the top can be wide enough to not hurt the transfers. OR just do a triple port sleeve? might be easier if the sleeve';s are being built. i did a triple port alluminum sleeve motor YEARS ago but never really got it finished the triples were kinda setup before the sleeve was pressed in. also triple was cut into the sleeve and then matched after it was all done the tunnels ended up being pretty small tho.

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post pics of the motors. !!!!!

 

421stocker are capable of around 55ftlbs of tq and 85ish+ hp with a non bridged exhaust and std intake.

 

but i'm curious. the motor would probably need to be pretty big to necesitate r intakes. cubs have proven that. the bridged exhaust is kinda known to crack because of the thinness of the bridge. the top can be wide enough to not hurt the transfers. OR just do a triple port sleeve? might be easier if the sleeve';s are being built. i did a triple port alluminum sleeve motor YEARS ago but never really got it finished the triples were kinda setup before the sleeve was pressed in. also triple was cut into the sleeve and then matched after it was all done the tunnels ended up being pretty small tho.

I gotta get on a real computer to get a new photobucket account set up to get pix. Man it would be so nice to upload directly from a smart phone.

By the way, did David Hasselhoff just call me a homo?

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I gotta get on a real computer to get a new photobucket account set up to get pix. Man it would be so nice to upload directly from a smart phone.

By the way, did David Hasselhoff just call me a homo?

 

 

what kind of phone u got i got a motorola droid and it has the app photobucket works pretty well on my phone can upload right on the phone of your pictures/videos just letting ya know

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Do the relief holes go all the way through the piston? Can you put some relief holes on the intake side as well? When I tore down one of mine this winter, the intake bridge area on the piston was scarred deep. You could feel it with your finger where the area had eroded. Still had 210 psi upon tear down, though.

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