Topic: TAO --- The South Seattle Cafe Project

[Jerry Rxman Griffin aka MuthaF'er]

Check with our own horse trader Bill Benton. He'll have everything you need. 

[SOHC4 Cafe Racer Fan]

Really glad to hear you are sticking with it!

[Jerry Rxman Griffin aka MuthaF'er]

If you're thinking K top end try to find a 392 head from a late K or early F. The Japanese rider, Mr Honda actually, at The Salt had a .5mm over piston kit with a stock 392 head and a Yoshimura Daytona cam by Yamiya with 34mm carbs and set a record of ~125mph. I saw the 392 on it and expected to see some porting and bigger valves but when I turned it over I was really surprised.

[SOHC4 Cafe Racer Fan]

Never heard of that before. Not sure how hard those are to find?

Well, that Yosh Daytona cam isn't exactly cheap!

[Retro Rocket]

Never heard of that before. Not sure how hard those are to find?

392 heads are everywhere Brandon, F0 and f1 had them and the k7 and k8 had them, I have 2 of them...

[70CB750]

F3 head is 410.

[Blackfin5]

Glad to see you're staying the course, brandEn.  Just stock up on Ballast Point pale ale.  I'm beginning to feel your frustration though.  TAO was some of my inspiration to become an F'er.

[Jerry Rxman Griffin aka MuthaF'er]

Ok so let me see if this is correct...


392 heads were installed on F0-F1 and K7-K8 heads. They are different from the early K heads AND different from the F2-F3 heads?
will the 392 head work on my F3 cylinders and Wiseco pistons? I need some schooling on the differences here. Kinda intrigued a bit.

Yes, the 392 head was used on the F0/F1/K7/K8. As far as the earlier K heads the combustion chamber is shaped differently and helps account for the slight bump in compression ratio and better performance. They have the standard size valves, 32mm intake and 28mm exhaust.

As far as your 836 Wiseco pistons, are they specifically for the F2/F3 engine? If so it won't work. The CruzinImage kit will work. If your Wisecos are retro fitted non-F2/F3 pistons for the earlier engines as some guys have done then they will work. The larger F2/F3 piston domes won't fit.

Easiest way to blend pre-F2/F3 engine top ends to a F2/F3 bottom is to also use earlier (or K7/K8) cylinders due to the change in oil returns. The F2/F3 eliminated a couple oil returns in the head and jugs. This doesn't mean you can't MAKE them work together but it's much easier to just use the earlier barrels too along with the non F2/F3 head. It'll bolt right up without modifications that way.

One other difference is in the K8 'intact' 392 head. 'Intact' meaning one that has the original hardware also vs a bare head. The K8 used stronger valve springs from the F2/F3 which is a good thing. However it also used the keepers from the F2/F3 which means it's valves had to have the keeper grooves changed which isn't a bad thing but even though those valves were different per se due to that reason they are still 32 and 28. Older valves can be used in the K8 392 head as long as the older style keepers are used also.

The heads should be fairly easy to ID. As mentioned the F2/F3 head is a 410 and the F0/F1/K7/K8 head is a 392. You can find these ID numbers on the top rear fin near #3 intake between #2 and #3. You'll also notice that the 392 head does not have the 'shrouding' by the plug hole in the combustion chamber. My K8 392 head also has 'K8' hand stamped next to the 392. Don't know if this is common or not.




   

[BPellerine]

the k8 stuff should be cheap for a top end and would offer options the f3 stuff does not as stated.bill

[chewbacca5000]

Yea I see that stuff for sale all over.

My F3 head still has good parts. I wonder if I could use the Cycle X heavy duty springs and alloy retainers on the 392 head stuff?

Way to dig in there Branden!  I think we are all happy to see you stay the course.  Looks like you did not have enough piston to bore clearance and it got pinched, but could be wrong.  As much as I would like a high compression forged kit they are a little tougher to get right.  For me I am sticking to the flat tops.

[chewbacca5000]

Does not look like anything wrong with that head at all.  Sounds like new set of jugs and a cruise kit will put you back in business.

[BPellerine]

yes you can use your springs and keepers as long as you have the the correct valve retainers ie clips.as stated f2 f3 k7 k8 have diff grooves in the valves.nobody but your hairdresser will know!haha bill

[Tews19]

Wow you have jumped in there and got the engine apart very quick! The marking in the cylinder look as if something was caught or possibly a ring somehow became jarred???

Glad to see you back at it though! Following the "Resurrection of Tao"

[Tews19]

This may be a crazy idea but does that piston have the ring clips, I forget the proper name that holds the piston on the arm that holds to the rod? One on each side?

[Jerry Rxman Griffin aka MuthaF'er]

Check cylinder and piston roundness perhaps? Diameters/clearances? Bearing clearances on that 1 cylinder? 

[Jerry Rxman Griffin aka MuthaF'er]

Mains and or rods. Thinking looseness could have allowed the piston to rock some?? Just some things I saw with my failure.

Were the crank oil passages to the piston bearing all clean and clear and flowing well? 

[calj737]

First impression was a failed wrist pin circlip. But the piston seems intact. That would point me towards the rod bearing and/or rod bolts. I suspect you checked the torque when removing the rod caps?

The only other possibility I could see is foreign material entering the chamber and wedging between the piston and cylinder wall, then dropping into the pan. Checked there for any metals? It does seem quite odd..

I don't see any evidence of the clearances being at issue as these would normally not be isolated to a single area on the piston. That scratch would indicate that the cylinder or piston, would have been extremely out of round and not so for long. Whatever made that happened only briefly, in my opinion.

[calj737]

I dont think that was the case. I actually think it is very improbable as to being the cause.

To my eye, it had to be either a rod bearing going wonky, or foreign object. I'm leaning towards foreign object almost as the scratch is not continuous across it's width. That would say to me, alloy not steel. But I'm speculating...

Is there any wear in the top end that could have perhaps dropped some sheared alloy into the intake side of the combustion port?

Those are forged pistons right? Incredibly high quality and "out of round" would be nearly impossible in my opinion. Also if Ken did the machine work, then the bore is straight and true too. Overheating as a cause? With street riding under your experienced hand? Completely hard to believe.

I just go thru those possibilities and deduce them as very unlikely. Which leads me to foreign object, or rod-oriented failure. If you can locate the new head, I'd replace just the single piston and a new sleeve and rock it back together (after resolving the issue).

Input on other topic: you can treat the skirts of those pistons with Dry Film Lube to aide in cold starts and help reduce friction/heating of the piston. Also, I'm a big fan of thermal coating on top of the piston, especially forged alloys, to retard the heat transfer and improve the combustion efficiency. If you have the block apart, ship the slugs out and have them done. These are my 59mm Wisecos treated with both surfaces.

[iron_worker]

Detonation normally will take a chunk out of the top ring land or melt a hole in the piston. Did you happen to check ring gaps when you assembled it?

I think you should get all your bearing clearances checked before you go ahead.

IW

[Jerry Rxman Griffin aka MuthaF'er]

I haven't checked the rod bolt torque yet but I will now before I pull them off. I am going to have to measure those clearances anyway. I didn't see any metal or material in the bottom of the pan. How can a new piston and bored cylinder just become out of round? overheating?

Hopefully rod bolts and nuts are still available from Honda!

It happened on mine but was caught during honing. You have to remember that the original cylinders have to be removed, the block has to be overbored then new sleeves PRESSED in and bored. I was told that as #3 or 4 ?? was pressed in it distorted #4 or 3 ?? and it was only discovered during re-honing. Keep in mind that mine was rebuilt the second time with only one sleeve initially needing replacement due to much worse piston/sleeve damage than your's. If they are all replaced and bored together then honed they should all remain round.   

[chewbacca5000]

Well I don't think I will ever know for sure. When I get more time to look at things more closely and clean everything up maybe something will pop up. I still think the pinging may have played a big part. It was coming from that side too. You gave me some things to keep in mind when I dig a little deeper for sure. Thanks for the input.

The F2 rod bolts are much stronger than stock.  Do not reuse the rod bolts they stretch.

[Stev-o]

How many hours on that motor since rebuild, brandEn?

[seanbarney41]

F3, the bike that took the "dependable" out of "Honda"...I have a strange love/hate relationship with mine as well.  It took a full year to get the damn thing running and riding. (and it does not even begin to be as trick as TAO)  Then it ate it's camshaft in the first 10 miles.  Pulled the motor, replaced with k6 cam.   Made it 1000 miles before valve cover gasket catastrophically imploded.  Pulled the motor, replace valve cover gasket with OEM this time.  Another 2000 miles and the new OEM valve cover gasket failed in the exact same spot.  This time I have just *fixed* it and it's been good for about 900 miles.  The motor still needs to come out again to replace the dimpled valve tips so it's gonna suffer until winter.  All this in addition to 2 faulty key switches, one cracked stator cover and a cracked oil pan...all of this since April.  Gotta love the 630 chain though, has been no trouble at all

[bwaller]

Sorry but I didn't take the time to read way back, but obviously there was a lack of oil to the crank. Were the oil restrictors in place in the head? If not the crank would suffer.

[Jerry Rxman Griffin aka MuthaF'er]

I agree on the lack of oil. Without seeing it in person it looks like the flow to that one rod journal was restricted but the other ones also just not as bad. I'm wondering about crap plugging the oil passages in the crank and or the oil pressure in general. Also I'd maybe question the clearances?? Matched case halves?

My crank and mains was quite a bit worse. It had a well defined raised groove on one journal. Send it for lightening and polishing of the journals and see what he says.

I can PM some pics if interested.