4 mil engine build

[plumcrazy73dodge]

I want to build a 4 mil set up since my engine locked up....

 

What set ups are out there that are reliable.....Once I order the crank kit....whats a recommended Top end? should I go .30 over?

 

What are you running and for how long has it been working out for you...

 

This is going to be the occasional MX, mostly open trail use...some drags

[T_Shee]

you should only bore as much as you have to. what is the bore now?

[elwilliams13]

I got a hotrods crank on mine It has been reliable so far had it in since about September. As for pistons, Wiseco 795 is what I have. They have an excellent reputation. I Have run it hard with 180 compression using vp c-12 fuel and castor 927 and it runs great. Mine is set up for trail riding with PT mid pipes. Pipes will depend on your riding style. The biggest improvement I saw was the porting I had done. They port the cylinders for the new extended stroke and it really compliments the motor. That can also be modified to your riding style and how you want the power to come on, lightswitch or broad and smooth! Give me a PM if you want the name of the guy that did mine. And bore out only as much as is necessary otherwise you are taking life from the cylinders IMO. But ask around alot of good people on here you should get a bunch of good advice.

[GASSRX]

yes the porting will help out alot on the 4mm setup and boring i would only go out as much as needed.. the port timing will be off cuz of the extra travel of the piston on the stroke.. i recommend not running a plate or more gaskets .. cut the head to allow the piston to clear .. CPI in frames work well on this sett up.. they work well in the trails as well as drag racing.. carbs and porting with the cpi's will scream..

[plumcrazy73dodge]

yes the porting will help out alot on the 4mm setup and boring i would only go out as much as needed.. the port timing will be off cuz of the extra travel of the piston on the stroke.. i recommend not running a plate or more gaskets .. cut the head to allow the piston to clear .. CPI in frames work well on this sett up.. they work well in the trails as well as drag racing.. carbs and porting with the cpi's will scream..

 

Right..I am slowly finding more info on what to do/not to do....I have the engine apart now so I might as well just do...I have seen where you have to alter the case for the stroke of the crank? But some 4 mil set up do not require it....is there a good/better company that desings the actual cranks....I am going to get the crank and rebuild the bottom of the engine then see where I am at for the top end based on waht I hear/research...I will be running the PT mids with the fatboy silencers...I just dont wanna have the crank freeze up in the future..anytime soon.......what is the lifespan on cranks/crank bearings??

[vulvafan537240]

Right..I am slowly finding more info on what to do/not to do....I have the engine apart now so I might as well just do...I have seen where you have to alter the case for the stroke of the crank? But some 4 mil set up do not require it....is there a good/better company that desings the actual cranks....I am going to get the crank and rebuild the bottom of the engine then see where I am at for the top end based on waht I hear/research...I will be running the PT mids with the fatboy silencers...I just dont wanna have the crank freeze up in the future..anytime soon.......what is the lifespan on cranks/crank bearings??

 

4mill cranks do not require any case mods. i think the most common 4mill crank is the hotrods crank. it is highly recommended that you have your crank trued and welded. most companies (F.A.S.T. racing for example) can weld them for you. as far as lifespan goes, they are just as reliable as stock.

[GASSRX]

4mill cranks do not require any case mods. i think the most common 4mill crank is the hotrods crank. it is highly recommended that you have your crank trued and welded. most companies (F.A.S.T. racing for example) can weld them for you. as far as lifespan goes, they are just as reliable as stock.

 

i would spend a little more and have that done as well save u so trouble down the road.. on the 4mm u wont need to cut the cases but it is recommended to run the long rod and get the special pistons from wiseco as well.. if u have any questions feel free to pm me

[plumcrazy73dodge]

i would spend a little more and have that done as well save u so trouble down the road.. on the 4mm u wont need to cut the cases but it is recommended to run the long rod and get the special pistons from wiseco as well.. if u have any questions feel free to pm me

 

Right I would definatley get it trued and welded.....could I weld it myself??? or not even worth the time? I am going with the long rod set up as well after reading about the problems with the shorts.....I just want the best set up for reliability.....I am doing it myself so I want it right....I can restore cars. I can handle the banshee engine...I rode it for like a total of 3 hours.......best three hours ever.

[GASSRX]

Right I would definatley get it trued and welded.....could I weld it myself??? or not even worth the time? I am going with the long rod set up as well after reading about the problems with the shorts.....I just want the best set up for reliability.....I am doing it myself so I want it right....I can restore cars. I can handle the banshee engine...I rode it for like a total of 3 hours.......best three hours ever.

 

if u have a tig it is very possible for u to weld them but most are held in a jig so they cant pull// meaning warp or twist.. in the long run i would just send them .. im sure there are tricks to that trade plus being a twin it might get crazy.. if it was a single i would say have at it but on those cranks... i wouldnt and i have built alot of motors....

[Wiz]

TZ bearing no matter what crank you buy especially the hot rod set-up......