some new goodies

[Jscobey]

JE high compression 11.5:1 pistons



900RR and SP1 front wheels for street use. current VTR and SP2 wheels will be for the track

[Jscobey]

whats all the OEM parts that i am going to need to install these. i figure its cheaper for me to buy them than to have the mechanic buy them because they always up charge for things.

the pistons came with the pins and the lock rings for the pins. i know i need the piston rings but do i need new con-rods or anything else?

if you could list the numbers from http://www.bikebandit.com/houseofmotorc ... 424#sch907 and how many of each number i will need id appreciate it!

[Stephan]

if your pistons are std bore, at first you need to verify wheter you can use them in your engine with std piston ring size. Cylinders can be out of tolerance. Maybe you did before, you should :-)

[Jscobey]

if your pistons are std bore, at first you need to verify wheter you can use them in your engine with std piston ring size. Cylinders can be out of tolerance. Maybe you did before, you should :-)

i had a conversation with roger ditchfield about that same topic. he advised me against oversize pistons for a number of reasons such as my bike only has about 25,000 miles which he said he doubts would be out of spec, and also i can always bore and sleeve to 98 if i needed to. his exact words were "Unless you have had a major engine problem I cannot believe that you will need a rebore and/or liners"

he also aid hes seen some bad results using oversize HC pistons. thats why i got them in STD 98mm bore.

[Stephan]

Ok, I planned to do this mod this year and searched some cases where os pistons were needed. That is why I will measure it properly before I would buy new std pistons. I talk about os piston rings you can order as oem from honda, not overbored engine.
But maybe I am too cautious

You need at least new engine gaskets and rod bolts.

[lloydie]

I'll be doing hi comps to the track engine this coming winter but I too will get the bores measured and checked before I order just in case I need +.25 or .50 os

[darkember]

Just remember to put the pistons the right way round, ask our resident guru Tony what happens when they aren't correctly installed. Ouch

http://www.vtr1000.org/phpBB3/viewtopic.php?f=7&t=30650

[kenmoore]

Make sure that you have a good ring compressor and get new rod bolts to be on the safe side.

What about decking the heads?

[Jscobey]

Make sure that you have a good ring compressor and get new rod bolts to be on the safe side.

What about decking the heads?

Decking the heads?

[lloydie]

Skimming the heads to rase compression more

[Jscobey]

I don't want anymore compression. To much is hard on the internals according to roger D. He told me not to do anything of 11.5:1. In fact he said optimum is 11.1:1 which he said JE makes although I have yet to find any mention anywhere of JE making anything other than 11.1:1

[VTRDark]

don't want anymore compression. To much is hard on the internals

And he's right, best to take Rogers advice. As it stands you need to think about the extra heat produced in the cylinder, as the heat moves the max peak pressure (timing) of the burn closer to the piston crown on it's way up and will need to use a higher octane fuel.

See if you can source an ignition retarder maybe. You should possibly think about sourcing a larger oil cooler, maybe run cooler plugs. You could even go as far as changing the rad cap so it don't build up so much pressure in the system and get so hot. Run the carbs a little richer to aid cooling, but a retarder would be better as too rich will leave traces of unburnt fuel behind and create carbon build up which could cause spontaneous combustion pre-ignition. You do realise you are opening a whole can of worms installing these.

I would like some mori pistons as they are slighter less compression and IIRC I think you can get away with running lower octane fuel (standard pump gas) with them. But as they are getting harder to source and usually a lot more expensive I will most likely end up with JE's. Or maybe I will skim the heads with standard pistons and play with cams instead. Or oversize standards and skimming the heads, now there's a thought.

(:-})

[agentpineapple]

iirc tony use's an sp1 oil cooler, as do a few others on the forum, you can also fit a fan to the lhs rad to help cool the bike..
as carl said its a can of worms, but who said chasing bhp is cheap and easy....

[tony.mon]

It's all ok, IMHO if you aren't stationary for long, fitting high comps and then trying to use the bike for a city commute is asking for trouble.

Hmmm, that's exactly what I'll be doing, oh, well, let's see what transpires.

A four-row oil cooler is a good idea, but only assists when your'e moving. An extra fan is probably more use, or simply fit an over-ride switch and idiot light to the one you already have. Simply turning the engine off at lights is fairly effective, if you can see that you'll be there a while.

I tried to find higher compression pistons than JE's, simply to have a play and see if anything was better or worse, but ended up with JE's as nothing else fitted the budget. CP (now part of JE) used to offer something a little lumpier, but the importer says not available any more.

I seem to recall JE only offering .5 oversize, or maybe that was Honda for the rings, either way a .25 over wasn't an option last time I looked into it.
.5 over won't make any difference to power or torque, though. I am currently looking at some alternative ring suppliers atm, to see if quality/cost can be improved.

Having pulled apart a few of these engines, bore wear isn't usually an issue. You'll need to break the glaze, but a light touch with a fine hone is all that's needed; keep it straight and vertical to the bore, of course.
But finding someone who is capable of reboring these (because the cylinder is at 45 degrees to the crankcase split) is tricky.

re the ignition retarder; it's already quite conservative as standard; I usually run a 4 degree advancer (making the spark occur earlier than it would in the standard setup) which also make the engine run hotter, but not by much. I also run Super unleaded (98 RON) to prevent knocking , (pre-detonation due to compression) which damages pistons and valves in short order. That's why there are risks associated with both increasing the compression and advancing the ignition, both together compounds the issues.

However, as standard these engines are in a low state of tune, and there's a fair way to go before there's any damage caused.
If you disregard the damage to my piston caused by three snapped-off valve heads, the engine had no signs at all of predetonation, running JE's and a 4 degree advancer, with mostly 98 RON.

You can use 95 RON if you can't find Super, by the way, just ease back a little from completely thrashing the nuts off it. I used to use it for motorway journeys or cold days, when I wasn't going to be troubling the rev limiter overmuch.

More importantly, there's loads if clearance between the standard piston crown and the valves, even at their closest point, with minimum valve clearances, and so "decking" is also easy and safe, but remember to dry-build the engine and measure the valve to piston crown clearance every one degree of crankshaft rotation before properly building it, just to be sure.

But Carl, an ignition retarder?
no.
Not unless you'r planning to try to run it on Methanol, maybe Nitrous.

Lastly, some people can afford Carillo rods, for example, but I've not found problem with std ones.
They're strong enough, but I don't have weight comparisons.

Just my thoughts, other's opinions are equally valid.

[Jscobey]

i dont see these things as issues and problems. just more mods. honestly i dont think ill have that much trouble keeping the bike cool. my bike has always ran pretty cool compared to what ive read about others. ive maybe had the fan come on once or twice since ive owned it, on the Hotest summer days.

if it does become an issue, than fitting a larger oil cooler will be in order. has anyone ever done a LHS fan? i thought my bike was missing the lhs fan when i bought it