Hi Guys,

I have had my cylinder re-bored to suit an 81mm wiseco piston, I have checked the bore for roundness, diameter and piston to bore clearance and everything is perfect.

When i checked the ring gap im gettin 0.019" - 0.020"?? for the full lenght of the bore.The wiseco guide that came with the rings said as a guide the gap should be 0.004" per inch of bore. Going by this im thinking my piston gap should be around 0.012". The Engine is currently un-modified so i don't require extra gap.

The service limit in the honda manual is 0.028"

This is a brand new 81mm piston kit from wiseco so i cant understand why the ring gap would be as large?

Any help would be greatly appreciated.

Thanks,

David

Show your math how you calculated your ring gap.

Why would you bother reading or discussing the Honda ring gap specs you threw them all out the window soon as you bought the wiseco you need to purge your brain of all the Honda piston and ring specs before you continue

The manual is my bible its hard not to take a peak

I just followed the honda manual on how to check the ring gap and read some guides on here also.

The wiseco guide stated 0.004" per inch of bore so the ring gap should be slightly more than 0.012"

Heres how i checked the gap:

I inserted one of the rings into the cylinder and squared it up using the piston. I measured the gap using feeler gauges. I carried out this process for the top middle and bottom.

Is there something wrong with the way im checking the gap?

Thanks

David

SHOW YOUR MATH

I don't understand?

What math is involved in taking the ring gap?

I thought you inserted the piston ring into the cylinder and measured the dend gap with a feeler gauge, am i missing something?

Thanks,

David

Sorry im with you now....

I calculated my gap by taking the bore diameter - 3.19" and multiplying that by 0.004"

That gives a gap of - 0.01276"

Thanks

David

The 3.19 is actual what you measured or just assumed?

Ok look on your rings by the gap on one side their will be a size stamped on them what does yours say?

This is the actual size.

The rings have N100 stamped on them.

Thanks

David

I have contacted wiseco with the details.

0.007" excessive ring gap doesn't seem normal to me for a brand new set of rings on a freshly bored cylinder.

Thanks

David

Yeah that was my next suggestion call wiseco if everything added up see what they say looks like your doing it right.

Have you relieved the exhaust bridge and drilled the holes in the piston?

It's and FL400 so it doesn't have an exhaust bridge or require holes in the piston as far as Im aware?

Thanks

David

Correct, however it still requires the ports to be chamfered and the piston to be prepped. Get rid of all those sharp edges. If I were you, I would clean up the casting flaws in the ports as well, makes a big difference.

I have went over the ports with a file to remove all the sharp edges as shown in the manual.

Is there a guide on removing the casting flaws from the cylinder that i could follow?

Thanks

David

I decided to have a look over my cylinder to see if there are any casting flaws i could notice.

here are some pictures of my findings and what i plan to do.



I plan to blend the material marked in red to smooth out the opening




I plan to blend the sharp edges marked in red to help improve airflow


Looking in from the bottom of the cylinder


I plan to blend the material marked in red to smooth out the opening


Looking in from the bottom of the cylinder opposite side


I plan to blend the material marked in red to smooth out the opening


Inlet


I plan to blend the material marked in red to smooth out the opening


I have heard people speak of removing the honda hump in the exhaust port so i was planning on blending this away to help with the airflow and polish the port to a mirror finish whilst im there.



Let me know what you guys think, would like to know if id be better leaving it alone or if im right in what im doing.

Thanks

David

Yeah you got the picture, you found the one Honda hump in the exhaust port their is one on the floor of the port too, you can see and feel it, also run your fingers up and down the transfer ports outer walls a few times you can feel the other Honda humps that need addressed.

Thanks for the guidance Hoser.

Here's my progress so far, just removed the majority of the material with some finsihing required and polishing for the exhaust port:

Sharp Edges Removed


Most of the hump has been removed, i may have another go at removing more before i final polish


Most of the casting marks removed from intake area.


I found these areas hard to get into with the pencil grinder so decided to leave them alone at the moment.



Is there an easier way into these ports Hoser?

If there is any room for imporvement on what im doing please let me know.

Thanks

David

Some you can get with a file and or a dremel tool to get it all and do the job right you need to spend some money http://ccspecialtytool.com/ then again the best tools in the world are no good if you don't know what your doing

That is exactly the kind of thing i need, ill have a look online for air tools similar to that setup that i can run with my compressor, if not ill use files etc as you recommended.

With all these flaws removed i am likely to notice any difference to the way in which the pilot performs or do these alterations simply improve fuel efficiency etc?

Thanks

David

Here's my progress for today. The only thing left for me to do is polish the exhaust port and im done

Humps Removed From Exhaust


Intake cast marks blended away


Eventaully managed to get into this area



No more rough edges



Thanks

David

now match your exhaust manifold/flange to your exhaust port

I have matched the exhaust port to the flange it just doesn't look like it because of the angle of the picture. Thanks for checking and keeping me right though. I'm getting excited to get it back together to see how it performs.

cool. you might have to step up in your jetting now as well. you should feel a nice power increase with these mods. good job.

[/quote]

David,

Don't polish the exhaust like a mirror it should be textured, there was a post a while back but I can't find it for you.

From what I have read there is not much performance difference between a polished port and a textured port, I'm doing it as its supposed to help reduce carbon build up and makes cleaning the port easier. Thanks for the advice.

Cylinder is just about finished, just final polishing the exhaust port and flange.



In the middle of building a pressure testing rig so i can perform a leak down test when i put it all back together. Just using the plans from the duncan racing website:



Going to use an expanding bung for the exhaust port, 38mm alloy plug for the intake and pressurise the system using the pulse line port on the side of the cylinder. I have ordered a 0-15psi gauge to connect to a tee fitting with 1/4 hose connections at either side of the tee.

The duncan racing guide said "Pressurise the system with 6lbs of pressure. The Engine must hold this pressure for 6 minutes without losing any air."

For anyone who has done this test before i was wondering if this pressure and time is suitable for a pilot and if you have any tips etc.

Thanks

David