Hs-40 build

[delray]

also I wanted to mention the lifters that I was talking about for the ohh-motors are different then the flatheads so there isn't any confusion when a person wants to order lifters. for example : lifters for the newer compression relief cam. on a ohh-motor the lifters are cup for the push rod.

I figure it would be better to keep this type of information with this engine build and it might make it easyer to understand with a picture posted of the lifter for a ohh-motor.

 

[markus]

markus did you get the lifters(37670) and if so were they the correct ones.

I actually have them in my online shopping cart working on filling an order up this week, 2 sest of those as well as some of the spacer washers for the compression release cams. Unfortuntaly the shipping makes those parts very costly so I gotta get some more items ordered up to offset it.

 

[delray]

little up date on how well the little hs-40 as been doing for me.
took the bike down to torquefest yesterday and ran it on there 1/3 mile track. i pulled the gear out of the jack shaft for 125 ft drags and installed a gear i thought would work well on the clay circle track.

big thanks for jeff son julian jumping on my bike so I could do some video shots.
after all the events where done on the track they let us back out on the track again and run are bikes.
I let julian run the hell out of it and he did. I was very impressed how well it would pull the bike around the track. bike ran over 10+ minutes between hot laps at 7000+ rpm's and never came unglued...lol
heres a good video bike pulling around nates modified hs-40 with a .080 wiseco piston and a 19mm dellorto carb on his engine. also past up some mild built 212 predators.

 

[Havasu Dave]

Very NICE! Sounds great! Couple of impressive bikes there, and great sound. I wish the video was a lot longer.

 

[dragracertpp]

Very cool! It sounded even better in person, glad you came out to torque fest this year

 

[delray]

here is another video I had on my phone. unfortunately it's still a short video but you can get little better sound of the bike by it's self. the audio is still not the best with just a cell phone.
"

"
I also just wet out and check the memory tach and it looks like it was spinning little more then 7000+rpm's.
crazy thing I road the bike too and road it hard and it never seem to flatten out for power. it just kept on pulling.
for now this little guy is going into retirement until I get a chance to tear it down and go through all the components I modified and if everything looks good I will refresh it and let it spin to the moon some more....

 

[delray]

little up date after a hard weekend at torquefest with my hs-40 engine. pulled the engine off the bike to give it a quick teardown and to use the bike it self for another project weekend race with a clone on it. one thing that I was very impressed with is how well the head gasket sealed to the block/head.

I'm going right back to the same processes as before. on my steel head gasket I use a product called prematex copper spray gasket. it seems to work very well for my application and maybe something to think about for anybody else that plays around with this type of setup.

couple light coats and your good to go.....

over all there was nothing really to look at. everything look to be in very good condition. just the normal carbon buildup. I did notes one thing right away when the head came off. the spark plug look little on the white side. I may have to jump up little on jetting and if I am correct the jetting was a 125 main,so maybe a 125.5 or a 126 should put it spot on.

 

[Havasu Dave]

I've used that for years on both small gas engines, and Japanese turbo engines like RB, JZ, and SR. Any of the aftermarket head gaskets will call for that copper spray or equivalent. I'm at 130, (900 feet) and feel pretty solid running it where I am, which I suspect is slightly lower RPM than what you are. Try a 130 and put the metering rod down in the hole by a notch if it stumbles. You're doing WOT with it anyway.

 

[Havasu Dave]

Forgot to say how oil free it looks. Considering the RPM, (and what it is) that engine is sealed up very nice.

 

[delray]

dave , I am going to put a torque converter on it to try some trail riding and the bike is getting it's full suspension back on it.. so I may be stuck with a lower jet. but in the future I will probably go back to a wide open driving and may have to play around with the metering rod too....

I thought you said you had a 125 jet on your hs-40 build? 130 is pretty big? not sure if this engine of mine could go that big?
little off the subject of jetting. this spring I have road couple bikes that produce at least 7+ horse power(clone engines with jet kit/air cleaner,header) and race against a few and this flathead can easily keep up with them....

can't wait to build a Big Bore hs-50 with a 255 dyno or isky cam....

 

[delray]

Forgot to say how oil free it looks. Considering the RPM, (and what it is) that engine is sealed up very nice.

Forgot to say how oil free it looks. Considering the RPM, (and what it is) that engine is sealed up very nice.

i was using a Valvoline straight 50w with a lot of zinc in it. not sure if that was the best when coming to the weight? zinc was a big plus.
without getting into high doller gokart racing oils I was thinking of going next with a 5w-30w with a lucas zinc additive and maybe stepping it up to a mobile 1 with lucas zinc additive. need to learn more on my oils.....lol

 

[delray]

also dave I am running a newer hs-40 .020 over piston that uses the thinner rings. they seem to to do very well. if I new what I know now I would of gas ported the piston and that would of been on the side right above the top ring with a half moon cut in the ring grove. but I don't have the tooling to setup a piston on it's side and indicated 8 times with a very small end mill. maybe in the future. right now I am looking at some cheap 5inch units on ebay that will work good for a next project build..

 

[delray]

mounted up a 30 series comet and took it for a spin. I was not happy at all with how it perform. it took forever for the engine to spin any kind of rpm's. just not enough gear in the bike to make it pull fast(no jackshaft). it felt like two city blocks before it could reach 6000 rpm's and this thing likes to pull at least 7000+. not looking to drag race it in a 1/8 mile. I want to do some trail riding and I need to motor to come on very quickly coming out of corners ...etc..

I could maybe try building a jackshaft in the rear extended arm or just see if a 7inch driven will fit. with out doing the math I believe a 7inch will pull about 1000 more rpm's at 125ft. I remember testing different sizes couple years ago for my drag bike and that did seem to help a lot. especially anything that likes to spin a lot of rpm's.
7inch fits ,but I will have to get a larger belt.....no problem.
about 1/8 inch clearance for the foot peg mount...…..plenty of room....

 

[joshua. c.]

so delray how well did the 7 inch work? was there a big improvement? if so I may have to try that myself.

 

[GustoGuy]

thanks ole4,one thing that really help on that rear arm was replacing the factory rubber bushing with a solid bushing. bike handles real nice now. before with the rubber bushing it was all over the place when riding it. it only took about 5mins of riding and I new the rubber bushing had to come out.....


also there was no intentions to make the bike look nice or detail looking. bike would be running on a clay surface only and it's just going to get dirty. so I just kept it flat black. going to have to go back in the spring maybe and clear coat it with a low gloss automotive clear on the gas tank,so the gas doesn't trash out the paint...:thumbsup:

Is this the bushing that you used. I want to do this since unpredictable handling in a souped up bike is not good.

http://blackwidowmotorsports.net/_17292a_is_the_new_swing_arm_bushing_1971_75.html

 

[delray]

so delray how well did the 7 inch work? was there a big improvement? if so I may have to try that myself.

yes and no josh,for my application I did not like it. I was looking more for hard acceleration in a very short distance at a very high rpm.
was it a improvement over a stock 6inch driven...…….yes
if indeed they say a 30 series unit creates 10 percent over drive. that would definitely not be good on a rupp bike with out a jackshaft to help it gear down better. so if I had to try it all over again on a rupp bike I would seriously look into a 20 series unit that does not have the over drive and also uses both sides of the belt to grip the pulley. me personally not a big fan of the comet torque converters. they definitely made only for low hp engines. to many mods that need to be done to improve the performance of them and that's like trying to reinvent the wheel with piece unbalance junk of steel. even when just using them in a stock forum. your always taking them apart and cleaning them and re-lubing them with the comet dry spray to keep them moving free.
josh or anybody else go's with a 20 series unit and a 7inch driven I would really like to here some feedback.

 

[delray]

Is this the bushing that you used. I want to do this since unpredictable handling in a souped up bike is not good.

http://blackwidowmotorsports.net/_17292a_is_the_new_swing_arm_bushing_1971_75.html

i made my part on my lathe. that replacement part he sells looks to be alot better too then the original rubber unit. nylon material going to be 10x better then the old rubber piece. like they said makesure the inside tubing is clean out good and you may have to grease the part and tubing up good and press fit it in.. looks to be a real good replacement forsure.

 

[GustoGuy]

Plus 45 year old rubber is most likely dry rotted to the point that it will not preform as it originally was designed for when it was built in the early 70's. Being that the bike only had 4hp it could get by with some sloppiness in the swingarm but with twice as much power it should be an essential upgrade since more speed and power will mean more flexing and likely failure of a dry rotted rubber coated bushing.

Thanks for the heads up on that swingarm bushing. I had no idea that it was an area of concern about handling. Do I need to use a punch to push it out of a tube inside of the bike frame? I guess since the bike is really old at 45 years that the rubber coated bushing is most likely just as dry rotted like the tires are.

 

[delray]

don't be surprised you may have press it out or torch it out and make sure the inside tubing is clean out real good before installing the new part. it might be a real tight fit.

 

[delray]

little up date on how my hs-40 has been holding up. I ran it couple weekends ago at the symco drags. it was a last minute thing for me to run the engine on my drag bike I use for 125 ft on clay surface. I was very impressed how well it did up against big block 5hp raptor motors. I end up racing to the finish line at 7200 rpm's with the fastest bike in my class and it was a split decision and my friend ben got the win with the 5hp raptor. maybe next year I would like to go back to a rupp frame and a clutch only setup and maybe a different fuel. no rules on the vintage class for fuel. this bike for me was just to heavy and to much drive train to move for this little engine and maybe a lighter jockey...lol

some day I will paint that tank....lol