Engine rebuild

[Phil-VTwin]

Ohhh i used to have that amount of play on a set of forged pistons, the piston slap when cold was loud but when warmed up and the pistons had expanded it was quiet as a mouse, apart from the 120dB exhaust!!

[benny hedges]

Secondly, I gave the cams to a local company who said they could do something but have had them for a couple of months and all I get is promises of "next week". So maybe I'll have to dig deep and get some Moriwaki's after all.

Either way, don't care 'cause I've just ordered the 11.5 to 1pistons from somewhere in California.
Only £103 wife-pounds, bargain.


Game on!

keep us informed how you get on with the pistons - i'd be interested to know what the valve to crown clearance is for obvious reasons, with standard cams and the (very expensive) moriwaki works of art.
last time i looked they were about 500 notes!

[oldbikeman]

Standard cams are:-
inlet open 20btdc
close 45abdc
Exhaust open 50bbdc
close 15atdc
These are pretty advanced timings for a road bike much more than most 4 cylinder sports.That's why it sups gas and has little bottom pull ,these cams don't work till over about 6000 rpm.I myself am a nippy rider but on A and B roads know I would be quicker on tamer cams.The XL motor makes over 100bhp which is a lot, it's timings are :-
inlet open 15btdc
close 30abdc
Ex open 40bbdc
close 5atdc
If I can get hold of some I,ll post results.Unless your going racing I wouldn't put in fancy cams.

[benny hedges]

thats what mines like, pulls your arms off over 6k but not much under 5

[Jazzscot]

So is it best to ride the storm above 6k revs then? When I did my bikesafe course the cops said that I should be keeping the revs high. Im always worried that im gonna feck it up when I ride in 2nd and 3rd round the twisty sections of road. As you guy say though I guess its meant to be ridden with high revs.

When does the limiter kick in?? I take it its the to stop you over revving and shaking the bike to bits like the washing machine in the other thread.

Jazz

[oldbikeman]

I bet a copper won't reckon much to you riding above 6K when he pulls you over.The Japs knocked this bike out in a hurry to nick sales off Ducati so a lot of development went out the window like the power characteristics so compared to other bikes it's a bit of hard work to ride well. The XL version which is a revolting mongrel actually had more time spent on it which makes it a better ride.Ride within our limits as this is one easy bike to get spat off.

[benny hedges]

So is it best to ride the storm above 6k revs then?

When does the limiter kick in??

you will find it is a different animal between 6k & the red line
that's where all the power is, lugging it around low rpm there's plenty of torque that pulls you around, but you're probably only making 39hp which sort of defeats the object of having a 100hp bike imo.

you will find it drops off above 9k due to the ecu (iirc) retarding the ignition timing to stop it revving (much) higher.
at 9.7ish- 10k it more or less kills the ignition, and you will notice a chronic misfire and loss of power.

try riding it hard to the limiter, on your favourite twisties - you will find it is very quick !!!
you won't kill it btw, if it was harmfull to the engine, mr honda would've set the limiter lower.

[tony.mon]

Jazzscot:
"When does the limiter kick in??"

Just take it to a race meet, then, in the campsite, after about 3 AM, start it and immediately wind the throttle back to the stop, cold engine and all.

Then you'll know what the limiter does, it makes the engine backfire and gets you a kicking.

[tony.mon]

Right, the rebuild is under way....
I started with this:


and then I took all these bits off:


and these bits:


And then I undid some bolts, and this happened:


Here's the other half:


And the main reason for doing this?


Lovely shiny 11.5:1 high comps.........

Just as a precaution I'm replacing the big ball bearing behind the clutch, which seems ok but I have a suspicion that it contributes to the graunchy clutch that some people have.

Next, gas flowing the heads ( once it's back together again, that is.....)

[Stratman]

so compared to other bikes it's a bit of hard work to ride well.

Can't say I've ever noticed tbh. Concensus always has been the the Storm is an easy bike to ride.

[benny hedges]

And the main reason for doing this?


Lovely shiny 11.5:1 high comps.........

Next, gas flowing the heads ( once it's back together again, that is.....)

when you do this tony, please dont forget to measure the piston to valve clearance for us, with standard cams...
need to know if i can do this with my high lift jobbies, without kissing the crowns lol

[tony.mon]

A small post-script, my spare set of cams finally came back from the cam-grinder.
He's only had them since May!
Still, by taking a bit off the base circle he's achieved a half mm extra lift (11.6mm for both) and a smidgeon more dwell (255 degrees) and all for £108 all in, inc dropping them off on my doorstep on his way home.
I'll be assessing back-to-back performance gains or losses measured against standard ones in due course, on the dyno.
Looking at specifications for other types and makes of cam, I might be get best power from a reground inlet cam and standard exhaust, I'll have to play on the dyno.

But for now, on with the mains, big ends, hc pistons, and get it back together.
A few weeks- it's Dyno time! (want to get it built, installed and run in first).

[tony.mon]

Right- update so far:
bores honed, top crankcase half thoroughly cleaned and back on the engine stand.

But the more I look at the main bearing shells, the more I think that although they look ok, while I'm there I might as well fit new ones- they're not expensive.
I'd checked them on strip-down, and they looked fine, so I decided to re-use them. But now I'm having second thoughts- ship-spoiling ha'porth/tar equation.

So that's as far as I got today!

A bit of a false start, TBH.

But soon, soon......

[Beamish]

Phhhhhhhwoooaaaaaarrrrr momma

Cant wait for the results Tony.

[rumpleforeskin]

interesting reading tone, nice pics too

with your new cams what will the dynamic compression ratio be?