Have you Decked the cylinder

[shook]

Thanks for you taking the time to reply.What I meant was when I was talking to LRD they said that the WEB cam is a good cam ,however they said that web grinds there cams and they do a slight mod to it.Now if they are full of it maybe sounds like a selling point to me.I was told that that cam works real well in the upper rpm ranges and that when it really starts to make power its time to shift.I would have to agree that on a larger displacement motor a larger cam would work well it only makes since that the bigcc motors need more cam to assist in the flow.

What in your opinion would be a better set up a 416 or 426. The web 450/451 cam or the hot cam.Oh by the way they dont that I know of but I do have a number(515)-402-8005if that helps.
Im going to send my head and jug to Hetricks to be ported and bored.I was thinking of just sticking with the 10.8:1 piston and like a 416, but have heard that the 426 is the better way to go.Im still uncertain if im should hard face the rockers or not the guy at Hetricks said it was not needed as long as I stay on my valve adjustments and keeop the oil changed,however web recommends it to be done but that is nothing but an insurance policy for them.Im then going to put the Hetrick pipe on it and either the 39 or 41 fcr.Then leave it alone.

My question on compression is that if what people are saying is right the 12.5:1 piston would probably work out to be 11:1 or slightly higher.That would be borderline on the race/ pump gas thing and definately add some serious torque.

[Matt Fisher]

In my opinion, the 450/451 cam isn't too big, I actually feel that my bike has decent bottom-end, excellent mid-range, and a good top-end. I have found myself bouncing off the stock rev-limiter a couple of times, indicating that the power hasn't dropped off significantly yet. I can't comment on whether or not LRD has a special grind made for them, I would be a little surprised though.

You may want to check out the website for GT Thunder- http://www.geocities.com/gtthunder.geo/gt1.html There are a ton of dyno runs on there. Their cam is the 450/451, btw.

If you're comfortable with the thin cylinder wall of a 426, get it. It's the same price as the 416 and will make more power.

The FCR carb, Hetricks pipe, and port work will all work best in the upper rpm ranges anyway. Not poorly in the lower ranges, but a higher-rpm cam should compliment those mods quite well.

I think you're misunderstanding the CR issue. The only piston that always seems to have a lower than advertised CR is the Wiseco 89mm. The 86mm JE, the 88mm Wiseco or any other piston may very well give you the correct CR. If you purchase a 12.5:1 piston that really gives you 12.5:1, then MUCH thicker gaskets might bring it down to 11:1, but you'll make less power than a piston with a small dome (or flattop) and standard thickness gaskets. I'm thinking that the JE and Ross pistons will be more likely have to the correct CR since they have small domes.

ref comp ratios


I finally measured the piston dome vol and came up with 10.89 CR using a stock bore JE 10.8 piston, xr head gasket, and silicone base gasket material.
The combustion chamber, valves, and piston have a thermal barrier coating on them, so that my have increased the CR slightly but not enough to make any difference.
Hope this helps!

[MIKE400EX]

A couple more notes:

1.) Took the head off the EX to check the torque on the head gasket again (Cometic Fiber composition w/ SS fire ring). The first time I checked it after about 1 hr. run time, it needed to be re-torqued. This last time, after another 2 hrs. NO re-torque necessary. Good idea to go back and check it if you have a composition type gskt.

2.) The holes that are left exposed after removing the de-compressor do not go thru into the oil passage, so there's no need to weld them up. No oil loss there!

3.) Honda puts a paint mark/indicator on the end of the outer valve spring that goes up (wider spaced coils). They do not mark the inner coil.

[PsychoDave]

bump

[86atc250r]

The FCR carb, Hetricks pipe, and port work will all work best in the upper rpm ranges anyway.

Actually, Matt, I noticed more bottom end gain with the FCR than I ever expected (actually I was expecting to lose a little bottom)... That's going by the seat of the pants dyno.

Must have something to do with less disruptions in the air path than the stock carb (Really, it has none, the stock carb has two)... But there was a large difference in the low end & mid with the FCR. I didn't notice much on top, but my limiting factor I'm sure is the cam I run. I'm sure there would be a huge diff in top end with a more aggressive cam - we've got one engine like mine with the GTT cam, but never ran it on the stock carb - mine's been run on both.

Hey guys I finally had some time to get into this engine and have some interesting findings.

Well it is truely a J&E flat top piston in there and it was looking like it was in pretty good condition. Had a little bit of carbon build up dead center but nothing to cause any concern. no big lips on the cylinder and no wear or scratches(more on this later) Does have some extra carbon around and on the valve area of the head.

The really ugly part is that the piston is stiing down in the cyl .028-.035" and I need to know if this variance is good. It has worried me and I am going to check the cyl for any warpage etc. I only have a good set of calipers for measuring but I know that my measurements are not off by .007" maybe a couple thou but not that much.

Matts original "senior moment" about the stock gaskets was correct. When the last guy put it back together he used a stk 85mm head gasket, I am not sure how much trouble this could have caused as the dome inside the head looks about the same size anyhow. (should this be machined to match the sleeve??)

Oh and do not worry about those little springs and pins from the decompressor they just wash around with the oil in the head


The rings look and measure up fine and the cylinder was looking good except for a small section of scratches at the bottm of the cyl on the back (looks like a little bit of piston slap) I have not speced up the pin yet but there were no signs of wear or problems. This was a little suprising as the piston really looked good like it was only in use for a short time. Maybe I am just used to the auto stuff whre there wrecked.

My question is what do I do for a measurement to deck the cylinder. I have the cometic .025 head and .012 base. If I go to .010 off the cyl will it be too low with the shorter measurement on the cyl to piston. Help!!!!

[powerslider]

Depending on where you take your measurements I would think there would be variations. I would measure above the wrist pin on both sides, they should be very close to the same. The piston to bore clearance will alter the readings at the front and rear of the dome depending on which way the piston is rocked in the bore. I would measure up the new piston and use the smallest measurement to base your deck height on.

Thanks
That would make sense and the "off" readings were on the front/back of the piston.

I only have these numbers as I am going to use the old piston. I am intending to change out the rings as long as I can get them before the weekend as I am having withdrawals from not getting out ridding

Does anyone have a opinion about fooling with the valves or not?? the quad and the head are only just over a year old and I was thinking of just "cleaning up" the exhaust valves in case there is any carbon building up. Should this be good?

And what about the amount to deck??? the most common measurement from the deck to the piston was .035, should I go with this?? (.035 -.020shaved= .015 = .025 cometic head gasket = .040 piston to head dim)

Just making sure I got this right before getting it cut down.