Has anyone here built a motor or added cylinders to a block to make a triple or multiple cyl motor? I need info on welding it like what kind of welder to use and rod or wire and things like that and how to go about building a crank like how many cranks I will need to make a multi cyl crank and some info on mod motors and books or plans things like that ....thanks
motor case mod questions
- Thread starter MODSUMMIT
- Start date
Anyone? Or am I just a crazy guy with a dream that's to far fetched?
Not crazy at all it's been done many times. if they don't build what you like build it your self. I have been wondering about these new 600s there so small i thought it wouldmake a good tripple 900 and nice and light and compact. Does any one know if this could be done> ? Polaris 600 07 or newer?
I realy wana take the 2 809 rotax cases I have here at home and chop half of one cylinder off and make a 5 cyl 2 stroke with a huge CC number just need more info before I undertake this project
This is a 1500 made from two Cat 900 motors.
The first step was to make a shaft the same diameter as the bearing journals. Then we cut the two cases near the middle of the PTO cylinder on one case, the Mag cylinder on the other, and measured and machined them down to leave about 1/8" gap. We ground out the stud holes on a bad cylinder to make it .040" wider than stock to account for the whole thing shrinking as it cools.
We bolted this cylinder across the gap and bolted all 4 case pieces to the shaft after heating them in the oven for a couple hours.
We sand blasted all the surfaces that needed to be welded. We used a Tig welder with 1/8" 4043 rod. We also had a propane torch that we used to keep the whole thing hot as we worked. Make sure not to weld the top and bottom half together!!
We then had a machine shop machine the cylinder mating surfaces and the mating surfaces of the case halves. We also had the case line bored.
If you've got any questions, ask.
The first step was to make a shaft the same diameter as the bearing journals. Then we cut the two cases near the middle of the PTO cylinder on one case, the Mag cylinder on the other, and measured and machined them down to leave about 1/8" gap. We ground out the stud holes on a bad cylinder to make it .040" wider than stock to account for the whole thing shrinking as it cools.
We bolted this cylinder across the gap and bolted all 4 case pieces to the shaft after heating them in the oven for a couple hours.
We sand blasted all the surfaces that needed to be welded. We used a Tig welder with 1/8" 4043 rod. We also had a propane torch that we used to keep the whole thing hot as we worked. Make sure not to weld the top and bottom half together!!
We then had a machine shop machine the cylinder mating surfaces and the mating surfaces of the case halves. We also had the case line bored.
If you've got any questions, ask.
Thanks. And another question I have is when I mate different cylinder like I wana put cylinders off a doo twin 800 on my case which is a 809 triple case do I just weld in the holes with the same filler rod as u use to weld the case? And the drill and tap new stud holes in the case?
As for the head too I wana put dual plugs per cylinder to make it more eficiant and run better since iam making it such a high cc engine so do I have to get a custom head made or can I do some cuting and weling and machining and filling to a stock head?
Ttt
I understand what you are trying to do and good for you, but slow down a tad. The Rotax 800 twin cylinders are cylinder reed and the 809 was case reed. Just a bit different. As far as multiple plugs per bore, the smaller bore of the triple will burn better even if you glue on 2 more cylinders. Good luck on your project.
oh ya i had to look at the case and ya i remember now its a case reed but because iam going threw somany mods i might as well build a plate and weld up the inlet ports on the case and make it a cyl reed if its posible? then i figure i would get more throttle responce or hope i will
Ttt
G
glhperformance
Member
you are better off using 800 twin cases and then cut them apart and start with that. it is asking way to much to use the case of the triple.
id catman I have a question, why would you use 4043 filler over 5356?
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I just thought it would be easier to use triple cases since its less welding and I already have 2 809 motors that need rebuilding so I thought I'd start there but the twin cases way does sound easier now and thanks for the info everyone
G
glhperformance
Member
you have to look at what you are using for pistons and cranks and rod pins for the pistons . that is why if you use the stock twin cases you can use the standard cranks to make at crank and then you would have the right upper rod pins for the pistons for that cylinder.
Well, we used it pretty much because it is what we had already.
We've used it before to patch cases with no problems, and it's been working here in two running cases for a year with no problems.
