helical crank gear

[RifRafRacing]

had my crank welded by APE ( stock 81 1100 helical gear).putting together a 1260/10.5 comp engine with 30-50 hp NOS and 7 inch slick/bar weekend warrior.what is considered the limit or cutoff point as far as horsepower goes for these cranks?some guys at the track say I may be pushing my luck not running the straight gear.I have been running stock(unwelded)gs cranks in street tire bikes for years,my current 1166 runs 9.7's all season without any signs of crank twist.

[lecroy]

This is a very good question. I have asked this about the helical gears, the stock transmissions and unwelded cranks.

If I was going to take a guess at this (really a guess) I would say it has more to do with your 60' times and how much weight your moving than enything. Oh, and how long you expect to be able to use it without damage. So, I would say every bike / rider combination would be different.

John once told me that the from his experience that the helical gears would be a problem once you got below 9.60. But he said he knew a lot of guys running low 9's and some high 8's. He said that these guys need to test the parts on a regular basis to make sure that things are not starting to move. Not like he hasn't seen a few clutches or cranks in his day.

I would call Falicon and run this question by them and see what they tell you. I am sure this is one of their most common questions. They didn't get their reputation by building 15 second parts for 6 second bikes.

One thing is for sure 100% correct. You NEVER run out of people's opinions at a race track!!!

[RifRafRacing]

yah,I think your right.Its the load on these parts at launch that causes breakage.APE didnt want to give me any #'s,as far as how much power this welded crank would handle.I think the helical gears under load try to drive the clutch basket in toward the cases.Im looking to make 170hp with this setup,just want it to stay together.RR

[lecroy]

To be fair, if all APE did was weld it, I don't see how they would know anything about the crank. After all they didn't take it apart and inspect it. They don't know how many miles are on the parts and how the bike was rode. Maybe you could do this in the mid 80s when these bikes were still new and get away with it.

One thing is for sure about APE, they make some killer wrist pins!!!!
Left is stock, Wiseco, MTC tool steel upgrade and APE



Yes, you are right. This is what happens. And three things can happen.
It can stay together. The basket can come apart. John said he had seen one spit the crank out the side. Strange, but I am sure he's seen it.

I can tell you that from what I hear and my own experience, the first question John asks is "What's this going into?". Then he will give you a streight up answer like "This is a good street bike crank" or "Thats the last time we can rebuild this one". I just don't see him ever using the "Customer is always right" as a business model and to be frank, I for one am very thankful for it.

I wish Jake would have wrote in, because I think he has to be close to what your wanting to run and I don't think his crank is welded or has streight cut gears. Only he and God knows how many passes he has made with that bike of his, but it sounds like a lot.

[RifRafRacing]

I know, and I believe that's a 1428 that he's running.Well it could be a mistake and a lesson learned with a set of fragged cases.Im just like everyone else with nos,a little more only satisfies you if nothing breaks and the et improves.Its hard to get to a point and say ok thats enough.

[rapidray]

The issue you MAY or mayNOT have will be the crank gear pushing the clutch hub into the cases. It has happened before but not to me. My bike with a seven inch slick runs 9 teens & 9.20s with a helical gear with no problems so far. This is the second, and LAST, season with this crank but I wouldn't hesitate to put it in my streetbike after this season! Good luck! Ray

[RifRafRacing]

thanks,Ive got a virgin transmission to have cut,hd output shaft and bearings.I got a quote from R&D,can ya suggest anyone else?

[lecroy]

FBG does all of our bikes, except mine. I had Pogue do it back in the 90's. I don't even know if they are still around.

Pearson also has told me that he does work like this but I have never seen any of it or know of anyone who has.

I have some parts I plan to send to Bill Robinson. I will let you know what comes out of it.

[rosco15]

I really like r+d. Great reputation. He will tell you whats wrong and then send you the bad parts back so you can see for yourself. I have heard good things about FBG, but have never used them.

[RifRafRacing]

contacted FBG,simliar plan of attack/cost as R&D.both are still dealing with heavy backlog from end of race season.

[lecroy]

FBG does all of our bikes, except mine. I had Pogue do it back in the 90's. I don't even know if they are still around.

Pearson also has told me that he does work like this but I have never seen any of it or know of anyone who has.

I have some parts I plan to send to Bill Robinson. I will let you know what comes out of it.

I ended up just shipping it to FBG. Bill was backed up for a month or so when I called. Turned out very nice. Machine work looks great. Parts seem to match up perfect. Not much was left of the original. They changed 5 gears when it was all said an done. I would use them again for this sort of work.

[RacingJake]

Hi guys

Looking at my clutch basket ring gear all I can say is the ring gear can flex about 1/4 inch before it hits the backing plate. It's easy to tell once it's broken. Over a period of time/runs it will crack due to flexing. The bad part is you can't inspected that area under the backing plate so who's to say how long it will last. All I can say for me is a 1000 runs was my limit and maybe since I only race on an 1/8 track that help alot too.



As for my crank I did have a rod bearing go out but I really think what caused that was to much advance timing causing one hell of a kickback, or maybe that is was just and unwelded 82 crank with over 24K miles on it.

Next year I'm thinking of going back with a 170 tire, foot shifting and no wheelie bars for something different.

[lecroy]

Hi guys

Looking at my clutch basket ring gear all I can say is the ring gear can flex about 1/4 inch before it hits the backing plate. It's easy to tell once it's broken. Over a period of time/runs it will crack due to flexing. ....

As for my crank I did have a rod bearing go out but I really think what caused that was to much advance timing causing one hell of a kickback, or maybe that is was just and unwelded 82 crank with over 24K miles on it.

Next year I'm thinking of going back with a 170 tire, foot shifting and no wheelie bars for something different.

I love that picture! Did Scotty come through for you? I think that the BIG savings you have is the small tire. There is some give to it. That last 1/8 I don't think puts a whole lot of stress on anything compared to the first 1/8th.

Ok, am I missing something or are you giving up on the 5's? It sure seemed like you were going in the right direction with it. Hate to see you throw in the towel when your that close! I know you can pull it off!

Good to see ya post again. Send the snow up North where it belongs!

[RacingJake]

Not yet, I know a guy with a ZX14 with a few mods too and we always have a close race and was thinking of putting back on my 1166 13-1 block and pistons and spraying the hell out of it.

The 5's are still on the radar for next year \\/

[lecroy]

I thought you were running close to the same bore I was. Why not spray the bigger bore with a smaller shot?

Or with the rod and basket going south, there is that GSXR motor on eBay. I am sure you could wedge that puppy in your bike.

What's in the works for a swing arm?