The Backwards Engine Experiment, 1939 Colson
- Thread starter bairdco
- Start date
Is the new motor as smooth as the last one? My Grubee vibrates to beat the band.
As far as your motor performance I think you attention to detail has more to do with power than anything else. A linear exhaust pipe will make more power on a two stroke. Dynometer test pipes are straight and always make more power than pipes with bends in them. Regardless awesome job on the bike! I wish I could come up with half the stuff you do.
As far as your motor performance I think you attention to detail has more to do with power than anything else. A linear exhaust pipe will make more power on a two stroke. Dynometer test pipes are straight and always make more power than pipes with bends in them. Regardless awesome job on the bike! I wish I could come up with half the stuff you do.
thanks...
yup, my new motor is smooth as glass. it doesn't even break a sweat over 45mph.
as far as the as the "attention to detail," i agree to a point, but i've done basically the same mods to a stock motor and the backwards ones just seem to run better. i'm sure it's a combo of the straight pipe, the shorty intakes, and everything else all working together.
as far as your vibration probs, all the Grubee's i've had are super smooth. maybe you're problems are coming from somewhere else. the obvious would be how it's mounted, but other things, like not having the muffler clamped to something, can really make some vibes.
yup, my new motor is smooth as glass. it doesn't even break a sweat over 45mph.
as far as the as the "attention to detail," i agree to a point, but i've done basically the same mods to a stock motor and the backwards ones just seem to run better. i'm sure it's a combo of the straight pipe, the shorty intakes, and everything else all working together.
as far as your vibration probs, all the Grubee's i've had are super smooth. maybe you're problems are coming from somewhere else. the obvious would be how it's mounted, but other things, like not having the muffler clamped to something, can really make some vibes.
the easiest way to tell is to hold your foot against the muffler when your bike starts vibrating (if you don't mind a little burning rubber) that's how i figured it out.
) that's how i figured it out.
Oh. So, you burnt your sneaker to prove a theory. That actually makes sense. I thought it was an accident from the way the "Hot -Foot Express" was set up. Watch, when my build is done - I will brace myself and do this. I think you may be right about where the vibes are coming from.the easiest way to tell is to hold your foot against the muffler when your bike starts vibrating (if you don't mind a little burning rubber
I like the backwards top end...
A roll of motorcycle header wrap will cure the hot foot.
COOL!
BBB
A roll of motorcycle header wrap will cure the hot foot.
COOL!
BBB
Re: burnt shoe. Why not poke the muffler with a piece of broom handle or something, instead? If the vibration quits then, you know the answer.
The backwards ones might run better because the Carburetor is facing the wind. So you get more air intake I believe. I've done this before (Make carburetor intake face forward towards the wind) and had a nice performance boost.
But for you to do the backward motor thing what do you do? Just change the places of the exhaust and carburetor? Or do you have to switch some internal parts too?
Also are the exhaust and carburetor holes on the engine like both in the middle or is one hole higher than the other? One hole higher on one side and the other on the other side is a little bit lower on the engine. (If you know what I mean)
But for you to do the backward motor thing what do you do? Just change the places of the exhaust and carburetor? Or do you have to switch some internal parts too?
Also are the exhaust and carburetor holes on the engine like both in the middle or is one hole higher than the other? One hole higher on one side and the other on the other side is a little bit lower on the engine. (If you know what I mean)
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ummm. these questions are answered in the first part of this thread's first page.
reversed barrel, and piston too...
reversed barrel, and piston too...
another word for cylinder, if you remove the four nuts that are visible on the head, this allows the removal of not just the head but also the cylinder, which apparently one can just spin around and have it work just fine. it's madness!
even crazier, the piston is ready to be flipped around as well? it's nuts. I love reading about this kinda stuff.
even crazier, the piston is ready to be flipped around as well? it's nuts. I love reading about this kinda stuff.
pretty much all of it's been explained in the first few pages. spin the barrel, spin the piston, match the transfer ports in the case to the barrel, make a shorty intake, bend the exhaust.
this motor's going on 3 years old now, had it on my race bike at the last tucson deathrace and at willow springs, and now it's back on this bike, and i ride it to work 30miles round trip everyday. still runnin' fast and strong.
this motor's going on 3 years old now, had it on my race bike at the last tucson deathrace and at willow springs, and now it's back on this bike, and i ride it to work 30miles round trip everyday. still runnin' fast and strong.
Nice. I like the skip-link chain. Maybe you should make the same style of sprockets for the motor so it will go with the theme. Okay, maybe not . . .
I've now seen a few people with their heads on backwards (dual meaning there?), and it seems to work just fine. I've been wondering how to deal with ground clearance issues on an expansion pipe, and I'm thinking that a backwards head would be a big step forward in figuring out how to route the pipe. I hate that most of the kit pipes and fleabay pipes lower your ground clearance by several inches. Went of a curb the other day and stripped a muffler stud pretty badly because the looooow pipe took most of my weight very quickly. I mean, a practical-to-ride bike should have a certain amount of ground clearance in order to handle the occasional "rough terrain" (aka curbs, potholes, etc.) that is often found in cities and suburbs.
Meant to comment on your bike. Didn't mean to rant about ground clearance and poor design qualities of made-in-china parts. I love your bike, just as I love any well made, well maintained machine (It especially applies to those machines that have wheels and go "VROOM".)
I've now seen a few people with their heads on backwards (dual meaning there?), and it seems to work just fine. I've been wondering how to deal with ground clearance issues on an expansion pipe, and I'm thinking that a backwards head would be a big step forward in figuring out how to route the pipe. I hate that most of the kit pipes and fleabay pipes lower your ground clearance by several inches. Went of a curb the other day and stripped a muffler stud pretty badly because the looooow pipe took most of my weight very quickly. I mean, a practical-to-ride bike should have a certain amount of ground clearance in order to handle the occasional "rough terrain" (aka curbs, potholes, etc.) that is often found in cities and suburbs.
Meant to comment on your bike. Didn't mean to rant about ground clearance and poor design qualities of made-in-china parts. I love your bike, just as I love any well made, well maintained machine (It especially applies to those machines that have wheels and go "VROOM".)
Seems like you have some experience with Oti@ 2-stroke oil, I have a brand new engine never started(thread... Blood Thursty) can I use it from the jump even though it has never been started?
I have a Puch hi comp head,Crmachineman modified piston,precision wrist pin & lower rod bearing,cylinder has been ported and resurfaced,Dellorto 15.15 carb, Jaguar cdi & coil and modified expansion chamber exhaust.
I'm sure about everything but the oil aditive.
I have a Puch hi comp head,Crmachineman modified piston,precision wrist pin & lower rod bearing,cylinder has been ported and resurfaced,Dellorto 15.15 carb, Jaguar cdi & coil and modified expansion chamber exhaust.
I'm sure about everything but the oil aditive.