0versteer
0versteer None
11/6/14 9:50 p.m.

ok, so how much weight do you think is too much for a bike engine car? (thinking engines around 100hp)

would 1000lb or less be the idea weight?

motomoron
motomoron SuperDork
11/6/14 10:33 p.m.

Here's a stock 1340 Hayabusa motor pushing 1,310# around Summit Point just fine. For street use, gear it correctly, and buy a good clutch pack.

1'13.01 Summit Lap - #51 Area 51 Racing Radical ProSport.

mr2peak
mr2peak HalfDork
11/6/14 10:55 p.m.

I'm guessing the transmission would be the weak link

fasted58
fasted58 PowerDork
11/6/14 10:57 p.m.

For extra assurance use a billet clutch basket.

Driven5
Driven5 HalfDork
11/6/14 11:26 p.m.
motomoron wrote: For street use, gear it correctly

Wich is often easier said than done. For street use, the close ratios do not typically allow for both a good 1st gear and a good top gear.

GameboyRMH
GameboyRMH MegaDork
11/7/14 7:16 a.m.

Gearing, oiling, having the right clutch and having a "cush pack" put back into the driveline are much more important, weight is almost a non-factor.

LuxInterior
LuxInterior Reader
11/7/14 10:19 a.m.

And don't forget that aero drag becomes a big factor when you want to go faster than about 75 mph.

yamaha
yamaha UltimaDork
11/7/14 10:48 a.m.

In reply to LuxInterior:

Actually most cars have a better coefficient of drag than bikes.

NOHOME
NOHOME SuperDork
11/7/14 10:54 a.m.

Gears do not look very strong on bike engines compared to cars. How long do you need this to last?

LuxInterior
LuxInterior Reader
11/7/14 11:38 a.m.

There was a bike engined low cost that appeared at High Plains Raceway a while back. It was cool. However, it was not fast.

44Dwarf
44Dwarf UltraDork
11/7/14 12:22 p.m.

When I started Dwarf car racing in 97 the gsxr1100's (1052 oil cooled motors) hauled ass in a dwarf that was 1380lbs per the rule book. never a clutch or trans problem unless the racer used wrong rear end gears and tried to race in second gear. When I go out in 2012 the stock 2002 gsxr 1000 was working great hauling 1240lbs

44Dwarf
44Dwarf UltraDork
11/7/14 12:27 p.m.

The real limit seems to be the drive shafts. Most adapters use the spicer PTO slip joint pattern and the tube that is for that size is small diameter and the shafts are long they typical run just over the 3rd critical speed of the shaft. If you can use a shaft with a center section as this will raise the critical speed of the shaft section back to a safe place and let you gear the rear low so you have more useful lower gears in the trans. with a 74inch roll out 4:10 or 4:30 would work great on the street.

Knurled
Knurled PowerDork
11/7/14 12:49 p.m.
yamaha wrote: In reply to LuxInterior: Actually most cars have a better coefficient of drag than bikes.

cd is equally as important as frontal area, and cars tend to have LOTS more frontal area!

Sanity check - a 170ish HP sportbike is often/usually artifically limited to 186mph, whereas a 170hp car will be drag limited at 130-140mph.

yamaha
yamaha UltimaDork
11/7/14 12:55 p.m.

In reply to Knurled:

This is true, but when you have similar power to weight ratios, cars always have the advantage in top speed.

Woody
Woody MegaDork
11/7/14 2:27 p.m.

erohslc
erohslc Dork
11/7/14 5:43 p.m.
0versteer wrote: ok, so how much weight do you think is too much for a bike engine car? (thinking engines around 100hp) would 1000lb or less be the idea weight?

Used as a wheel chock, and placed properly, nearly any motorcycle motor can handle vehicles weighing many thousands of pounds.

As jack stands, they are not as useful, the fins bend, and they are not too stable.

Knurled
Knurled PowerDork
11/7/14 7:12 p.m.
yamaha wrote: In reply to Knurled: This is true, but when you have similar power to weight ratios, cars always have the advantage in top speed.

Power to weight has nothing to do with top speed, it's power to drag.

0versteer
0versteer New Reader
11/7/14 10:09 p.m.

im not used to forums where people actually have useful opinions haha.

i have an MG midget, and a gsxr 1000 engine.

i was just curious if it was a feasible idea to combine the two.

i've been going over this build here and have come to the conclusion its more work than its worth.

Slyp_Dawg
Slyp_Dawg HalfDork
11/8/14 12:12 a.m.

we're the good kind of enablers, we will enable anything AND brainstorm ways to make it actually work

icaneat50eggs
icaneat50eggs HalfDork
11/8/14 9:32 a.m.

That build is stupid . Who cares if the engine holds together, the old car frame not self destructing is the real killer at 500 hp

Dusterbd13
Dusterbd13 SuperDork
11/8/14 10:19 a.m.
0versteer wrote: im not used to forums where people actually have useful opinions haha. i have an MG midget, and a gsxr 1000 engine. i was just curious if it was a feasible idea to combine the two. i've been going over this build here and have come to the conclusion its more work than its worth.

Damn you. Niw im looking fir an lbc again.

Knurled
Knurled PowerDork
11/8/14 11:45 a.m.
Slyp_Dawg wrote: we're the good kind of enablers, we will enable anything AND brainstorm ways to make it actually work

Your idea of "good" is a strange and sadistic one.

I think the neatest way to do a bike engined car would be to drive the original transmission with the bike transmission. That way you get the close gearing of the bike transmission times five different ranges, and you get reverse too. If that is excessive, you could eliminate all but two of the forward gears and have low and high ranges. And reverse.

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