I have seen Mr. Horsepowers 730 big bore kits on his site. but i have not seen any 800. Alot of people mention thanks to Mr. Horsepower my 800 ran great. Where might i find me an 800 kit or is this a custom job? What kind of HP are we talking with a 730 big bore, 46hv carb, race ported air intake and piped compared to the 800 with same features except change carb to the 48hv? Now to show my stupidity , do the big bores have to run on race gas or 91 with an octane booster work. Tired of following the pack and now i want to lead it. I would prefer to stay at the 91 octane but I know being fast is not cheap. One more stupid ? What cams make a good combo with these ? If i change the cams do i need to port the head and change the valves

 

The 730 and 800 have the same size bore of 105.5mm. The 800 uses a stroker crank which entails a lot more labor of splitting and machining the case. Although the bore size is the same MisterHP has 2 different cylinders, the 800 have a longer skirt. The piston is the same for both 800 and 730, right around 13:1 compression, definitely have to run 110 race gas with that. I would suggest you talk to Eric if you want to run pump gas, he may be able to get the compression down for you. But honestly if you are going through all this engine work use mize well spend the extra few bucks on race gas so you can run the extra compression.

I would definitely do the race head. I believe a stock bore with a race head is faster then a 730 with a stock head.

I don't think anyone has dynoed the 730 yet, I believe mine is the only production 730 running. MisterHP has some 800 dyno charts on his photo page.

As far as 800 vs. 730, at 4SW the 800 guys were saying that it was too much engine for dune ridding. My 730 was great ridding the dunes. Allot of that may be due to the cam selection. The 800 were running very aggressive cams while my 730 was running a milder cam.

I think its wise to stick with one engine builder, if your a going with HP research cylinder and head, it would be a good idea to also go with his cams etc.

 

Hey.. You might want to give TVI a call and talk with Gary..He is located up here in Oregon... He has a few motor kits for the Ds.He has a big bore 720 and a stroker 800 motor.Plus he has a great race head...He also is building turbo motors. He just took a bone stock 650 and bolted on a turbo charger..It runs GREAT and builds some great power...If you want his address or phone number..PM me and i will send them to you. He had built a lot of motors. The guys that have them love them and the motors are holding up real well..... [img]i/expressions/face-icon-small-happy.gif[/img]

 

You also might want to do a search on forum members that have products from both TVI & HP Research to see what they have to say about there results. I think there are five or more members that have both & there own opinions on these DS builders.

 

whomever u choose..i would stick with one builder for all your motor parts.call around and talk to some of the builders yourself. there are three or four great builders, u really cant go wrong with any of them...

 

As TheBigShow said, whomever you go with stick with that builder for all your motor parts. There motor kits are based on this & not mix matching.

Thanks Big Show, I forgot to bring that up[img]i/expressions/face-icon-small-blush.gif[/img]

 

Does anyone know how much stroke they have over stock to acheive the 800?

 

I believe the 800 is a 91mm stroke x 105.5mm bore