Just wondering if removing/replacing the cylinder heads requires the engine to be pulled out of the frame or can this be accomplished by other means?

Also, I got my bike dynoed again yesterday and, much to my chagrin, actually lost hp and torque since my last session (about 15,000 miles ago; peaks are now 102.1 hp and 65.6 ft-lbs vs 105.5 and 68.8, same dyno and operator, yesterday was cooler by about 10C or @ 20F). Does this seem normal to you guys or have mods led me astray? *sigh* The new curves mimick the old but are slightly below. The dyno operator (experienced tuner, was told yesterday these guys prepare the engines for Honda Canada's racing effort) stated that the loss is due to the engine getting "tired" (doesn't seal as well, but then it does have 55,000 miles on it, although it still purrs like a kitten). Assuming this is the problem, would new rings and a honing bring me back up to speed? If so, can this be done without removing the engine from the frame? I would assume it can be done by dropping the sump and removing the piston and rod assemblies from underneath.....

Sorry for all the questions but I know you folks have lots of experience and I am still learning (plus I don't have my own garage so I can't do this stuff myself; joys of apartment living).

Thanks in advance

cheers

 

Does the Dyno have a EGA? (exhaust gas analyzer) If it were worn pistons/rings then you would have more blow by and could tell by increased oil in the exhaust and your oil getting dirtier faster..

Cooler temperatures should = more power, not less. What mods have you done since the last session? It is entirely possibly your "improvements" actually lowered your HP.

 

Since my last dyno run I installed the Flo-Commander, gutted the intake snorkel, heat-wrapped the exhaust, added a lighter flywheel, and changed the chain/sprocket combo to 520 chain and 15/43 combo (with alum. rear sprocket). In theory, none of these changes should have had a negative impact on output (in fact, in theory of course, all of them should have yielded a very slight increase). I also removed the PAIR system (and plugged the vacuum feed). I didn't ask to have the EGA hooked up as uit was jut a spur of the moment thing and I was just looking to get a ballpark figure, which I got. WE did play around with the Flo-Commander setting (and noticed a difference in how the engine ran and on the power produced, proof that it works) to get a max reading. Again, there has been 15,000 miles of wear on the engine since then although in terms of running quality the engine seems to run as well (in terms of smoothness and throttle response) now as it ever has, which makes the result all the more surprising.

 

Its less than 3%. I'm not sure that is statistically even out of the reproducible range of things: different fuel? tire pressures? I wouldn't worry about it. If you were, get a leakdown as a starting point but 102 with stock internals isn't bad.

I'm sure the heads can be removed in the bike. People have described changing the rods/pistons via the sump and even honing cylinders etc, but to me that seems risky: I'm sure its dependent upon mechanic/skill, but with that many miles on it, to go to all that trouble and not assess crank bearing tolerances, other internal items when you alread have the engine out of the bike just seems penny-wise and pound foolish. Just my opinion on it of course.

 

Hmmmm...... dunno about that. I had my engine removed to do the job. I reckon that would be the way to go. You may waste more time stuffing around trying to do the shortcut.

 

You can have the heads removed with the engine still in the frame. But to access the piston rings and do things right, the engine needs to come out and the cases split. Worn out rings would bring the torque down and not horsepower, at least that's what the dyno operator told me.

 

The heads can be pulled without removing the engine, but like others have said if you're planning on re-ringing you really need to pull it to do it right as you'll want to deglaze the cylinders.

But, I wouldn't do a thing without a compression test first as it may be a big waste of time. I could be wrong, but unless you got the engine extremely hot at some point in the last 15k miles I doubt ring wear is accountable for the variance in peak numbers. Depending on the dyno, the difference may simply be in the SAE correction factors. I'd say if you're more than 5% difference between the front and back cylinders on a compression test, with 50k it may be worth tearing into the engine. Otherwise, I wouldn't lose any sleep over the 3hp.

 

Thanks, I don't think I'll be re-ringing at this time for many of the reasons listed. Also, further to e-mails with both Roger Ditchfield and Bob Hayashida at BVH, I think my snorkel mods were likely at least partially responsible for the drop in power (due to increase in turbulence in the airbox). In tesm of what is not due to the airbox (and it could very well be ALL due to this) I also find it hard to buy into such a drop in power due solely to the rings. It may be in part due to that, but also likely to some extent to wear on valve seats, for example. Given that I use it for sport-touring, I do not rev the engine very much (no need to, it hardly ever sees 7500 rpm) and I maintain the engine faithfully (oil changes every 5000 kms with Motul semi-synth and Honda filters, as well as using OEM air filters) I also take care to warm it up properly, not overheat it, and avoid short rides. As I said before, the engine does not burn any oil (no more than before) and runs as smooth as ever. I do, however, want to install the new heads once they are properly ported. My big debate now is cams or not, and decking or not. At the end of the day, it is purely a function of $$$$$ as I would just LOVE (oooh would I!!!!!) to do the full Stage 1 treatment but cannot justify the expense at this time.

Thanks for the input everyone

cheers

 

as soon as i read your tread i thought about the gutted snorkel mabe if you mucked around with jetting you could get some gains or you could just get another snorkel and be done with it. I dont know if id start tearing the engine apart over a couple horse power just dosent seem logical wait till it actually needs some work and in the mean time save for some high comp pistons for when your in there.