88B Upgrade

[scor]

Mike,

I've got an 05 Heritage with 20k miles, a SE air filter kit and SE sip ons. I'm thinking of changing the cams to gear drive and doing head work. I've read that I'm bettor off doing the head work before increasing the bore and can't aford all at the same time. I've got an 86 evo with heads reworked by Baisley (street port) and a Woods W6 cam that work great together. What do you suggest?

[Mike]

Scor, Going to cams along with head work will give the greatest gains. I question the author who recommends head work over the big bore kits. Going to 95ci from 88ci is by far the best bang for buck, at least from a torque point of view. The labor to R&R the heads is the same for the big bore kit, so there is no savings here. The cams will be same/same. If you are going to have the heads off, the additional cost for 95ci would be $280.00 (cast pistons and cylinder boring). The head work and cams will respond much better with the larger bore. If cost is an issue, consider staying with chain drive cams. The cams are typically less expensive and you save the cost of the $400.00 gear drive kit. We have not seen chronic failures of chain drives! The gear drive may also be mechanically louder. To address this you may need the oversize gears which can add an additional $180.00. The Wood Auto gear drive cams also cost +$130.00 vs S.E. chain drive cams. The total gear drive could be as much as +$710.00 vs S.E. cams. To be fair, with the milage on your bike we would recommend new tappets, chains and tensioners with a cam change. The tappets would be the same for gear or chain but the +$150.00 for the chains and tensioners could be applied toward the gear drive. Also note that the cam choices will be different for 88 vs 95 vs heads vs no heads otherwise each combo may be compromised and the performance gains not realized.
Having said all that, we offer two kits. The 211 uses the S.E. cast 10.25 compression pistons, S.E. 211 cams and stock heads for 88-92hp and 100-105tq. Add a set of heads and you have our 251 kit. We use Baisley's superstock ported heads and the S.E. 251 cams for 100-110hp/105-115 tq. Both of these kits are flexible as far as cam choices and gear drives. Your slip-ons and air cleaner will work fine with these kits. See our new Dyno library for charts on what others have achieved with these packages (and other combo's including 88ci). We are in no way locked into these kits and if you have more questions or want to discuss other possibilities please feel free to do so.
Regards, Mike

[scor]

Thanks for the feedback Mike. I like the idea of putting the $150 for chain and tensioners towards a gear drive. And I agree with putting in new lifters with a cam change. Years ago I tried to save $$ by not changing the lifters with a cam change. I ended up spending way more after the lifters failed and sent shrapnel everywhere!
The article I read about flowing the heads before increasing the bore was in American Iron, where they've been running an article about upgrading twin cams for the last few months. The article says the stock heads are more restrictive than the stock evo heads were and that the heads are frequently overlooked by people looking for more go fast.
Regarding the cam chain, I don't hear it making noise so I haven't considered checking for wear. Is that part of the 20,000 mile checkup?

[Mike]

Yes, the heads are more restrictive than the Evo's. It is to keep exhaust gas flow high, thus raising the EGT, to burn off emissions. But, for the minimal added cost of going to 95ci while the heads are off, it is really worth doing and we would hate to leave that much performance on the table.
The cam chains and tensioners are not part of any scheduled maintainance. We have not seen any rhyme or reason to the wear vs milage on these parts. I.E., we've seen tensioners near their wear limit (50%) as low as 7K miles on one bike yet others with 40K (most) are just fine. If I were to recommend a milage at which they should be checked I would say 30K. Most technicians would no doubt recommend replacement at that time, if any wear at all was present. Just to be safe and taking into acount the labor going in to inspect.
Regards, Mike