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Post by 71magnum400 on Mar 30, 2008 14:18:20 GMT -6
OK now I'm confused again, , i just looked at the 1976 motor mod post, i noticed they show that boost port on top of the intake, OK my 76 cylinders to not have this port, the motor i took out of the 77 had them, the motor out of the 76 cylinder are G44bw, and the motor out of the 77 nitro has G44BW and P stamped in it ! I keep hearing the 76 motors made better power then the 77-78 with seeing my 76 cylinders and compare them to the 77-78 i would have to argue that, all the ports are smaller and no boost port on my 76 cylinders. so maybe i have the wrong 76 cylinders ? thanks for the help in advance !  |
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Post by snosnake on Mar 30, 2008 15:09:20 GMT -6
I think you might have some chappy jugs and 77 nitro jugs.
THE 76 NITRO/MAGNUM are G44BWR
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Post by 71magnum400 on Mar 30, 2008 16:43:41 GMT -6
well that sucks  so know that i know this i have to appologise to anyone that i argued on the power with. but they now can understand why i did argue with them, they do not even compare at all ! SO do the 76 cylinders actualy make better power then the 77-78 ? if so anyone know what the change in the motor is ? |
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Post by wigman25 on Mar 30, 2008 17:31:25 GMT -6
What I have found through my experience is that the '77 G44BW jugs with the '76 pistons make the best combination for power output using OEM parts, but the '77 jugs with the Wiseco 'L' ring split-port pistons is better than any of them. Lighter pistons, a touch higher compression ratio, with the split ports that atomize the fuel better pushes the power curve up a bit but you get a better top end from the higher rpm you produce. You can spin the Xenoah 440 up to about 10 grand before you get into the danger zone. The Wisecos will make you run from about 8300 with the stock setup to about 9000 with the Wisecos, good for about 3-5 mph. Flip in a set of Boyesen 2 stage reeds, grab another couple mph. I'm talking lake racing here, not short run drags. Perfect lake ice with stock gears and no headwind you will crack the century mark with it. Anything over 9000 you start to lose power real quick because of the pipe timing, a better set of pipes would make a big difference, I don't know if they were ever produced. A Xenoah at 9 grand sounds better than anything I have heard in a 2 stroke. Good luck with your engine. Wig
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Post by snosnake on Mar 30, 2008 17:48:11 GMT -6
hey Wigman do you want to get rid of your Lil' Andy?
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Post by 71magnum400 on Mar 30, 2008 18:37:00 GMT -6
OK now thats the replies i like to see, so now let me ask this, i tore apart a 250 xenoah last week, i notice someone had drilled (or maybe they are factory on a 250) from the intake side to the left and right side of the intake port, these holes went rite into the transfer ports, how does this affect the motor? this motor has seem many years of abuse, the rod was broken and some serious mayham took place on the case and head , they cylinders look to be ok,and i got a set of boyesen reeds , it was a freebee so i thought i would salvage what i could, nut anyhow what is this little hole, i was told about it before but just curious as how much benifit it actuall makes in power oh ya and i also noticed that the steel bridge on the intake boost port was removed also so now its one big hole and not two, another hidden stock appearing mod? LOL, I am going to take a stab in 660 ice drags with it in stock class so i cant be changing a whole lot. YES i know that its a tough sled to make competetive but i have faith in it !!!
So what gives on those two little holes from the intake area to the transferports?
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Post by Ruppsforever on Mar 30, 2008 19:04:41 GMT -6
First off... you need to ditch them damn chappy jugs and find some BWR jugs to compare your 77 jugs to. No 1976 BWR 250, 340, or 440 has that steel bridge. Are you the person that has called me and has been emailing me about motor mods  On your 250 motor that has the holes on each side of the intake that connects the intake to the transfers..... Them are boyesen ports. It should allow the bottom end and transfers to fill with more fresh charge. I am going to build a motor and add these ports but at this point I can't tell you if there is a definite advantage. But there should be an advantage. Alot of dirtbike motors have these ports. |
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Post by wigman25 on Mar 30, 2008 21:03:26 GMT -6
I've seen the charge holes on the intake side before, never messed with that. I imagine if you have the bottom end corked and filled that would allow for the increased fuel volume that would be gained through the holes, right? Sounds right anyway.
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Post by wigman25 on Mar 30, 2008 21:07:00 GMT -6
I also agree with Josh - although the jugs will work on the Rupp xenoah, the Chap l/c motors weren't high performance and you won't get 50hp out of a Rupp bottom end with those jugs. Wig
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Post by 71magnum400 on Mar 30, 2008 21:52:16 GMT -6
NO i will not be using these cylinders, i will make pencil holders out of them for my office ! Yes josh that is me buggin ya, sorry, i was told the 250 xenoah motors came with this port hole drilled out so u was told all wrong on that, im just learning these liquid motor, i am more experienced with the tohatsu motors so if i am bothering you to much im so so sorry soooo what about the cranks? i noticed tonite that the case on the motor the chap cylinders came off is smooth, and the 77 Rupp motor has a finned case, but the crank in that one is junk/rusted, so are the cranks in the chap motors the same as rupp cranks i will just swap the crank, then the fuel pump will be mounted to the motor not just laying there loose. Ok now lets talk heads, the 77 has smaller combustion chamber then the 76 head, but that might be a chap head to ? but im thinking on using the 77 head and the 77 cowling just looks like a better set up to work with and no ugly filler neck on the outside of the hood. or and with that i was thinking of getting ride of that front bumper and using the Magnum style mounts, just looks better ! |
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Post by wigman25 on Mar 30, 2008 21:59:47 GMT -6
The Rupp has a finned crankcase made to handle the hp of the engine. The '77 head has the coolant gooseneck attached right to the head.
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Post by wigman25 on Mar 30, 2008 22:02:07 GMT -6
I don't think the cranks interchange
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Post by 71magnum400 on Mar 30, 2008 22:08:22 GMT -6
were can i send my 76 crank to be repaired if they are not the same?
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Post by wigman25 on Mar 30, 2008 22:18:56 GMT -6
Boy, you got me. I would think it would be easier to get ahold of a good bottom end, either new or used. I just bought a NOS bottom end for $150.00 - still in the wrapper.
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Post by racingelvis on Mar 31, 2008 8:03:39 GMT -6
1st of all i would like to say that it is not hard to make these motors hard to compete. i have worked on these motors ever since i got into rupps and these motors have way more potential than what a person may think.
the chaperal cylinder has the the same g44bw stamped in the side of the cylinder as the 77 cylinder, but totaly two differnt cylders. so dont get confused just by looking at the # if your ever at a swap meet or something. the 76 cylinder has g44bwr stamped in it.
the 76 rupp cylinder head and 77 cylinder head have the same conbustion chamber so that probly is a chaperal head you have also.
the boysen port hole's are a commen used port that engine builders put in the cylinders. we have been using it for years and makes a tremendous differnce on throttle response. it does make a motor make more h.p. but i cant tell you that amount becouse i just dont know.
the 77 crank is a better crank than the 76 crank. one more bearing and a beefier crank also. the 76 crank will work in the 76 case only and it is the same for the 77.
i have been to 3 differnt engine builders and got 3 same answers. the 440 77 cylinders are a better cylinder to start with than the 76 440 cylinders and the 77 cylinders will make more power. the 76 250 and 340 are alomost identical in the bottom transfer area as the 77. the 440 76 cylinder is way differnt. i have never did a full mod with a 340 or 440 but i can tell you that my 250 lc super mod really rocks.
2007/2008 250 l/c super mod race record
3 wins
2 seconds
plus i was hurt for 3 of the races so the sled did not compete.
if you need a crank rebuilt get ahold of me, i have 2 differnt crank guys that knows these cranks and i can get a you a good deal also. thanks, THE RUPP SHOP 715-592-4707. b.s.
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Post by wigman25 on Mar 31, 2008 9:23:09 GMT -6
Now that is settled, we just have to get Snake to admit that these liquids can run with (or outrun) the best of them. Wig
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