[Turbo DV8]

Well, I found one explanation for how Honda sells this bike for so cheap. So, I'm looking under the engine, admiring my new motorcycle, and I notice grey silicone sealant squeezing out from between the engine case halves. I could peelit right off with my fingers. Honda used no freaking gasket, just silcone all the way around, from the front of the case, near the base of the cylinder head, underneath, and back up the rear, above the starter motor and back to the rear of the cylinder head. There is excess silcone oozing out almost all the way around. I really cannot believe this was meant to be assembled like this!

It is common knowledge that using only silcone to seal anything that vibrates and is related to sealing oil is a no-no. Silicone does not fret well at all, and the seal will eventually fail. I've already seen a post where someone went out to his bike to find a puddle of oil under the engine. Far worse, visible silicone oozing on the outside means there is most likely silicone oozing inside the engine. This forms anything from thin strips of silicone to large chunks of silicone on the inside, just waiting to eventually break free, circulate in the oil, then be sent to some tiny oil jet or passage to clog it, causing catastrophic engine failure. it is not uncommon to see that in engines assembled using silicone.

I simply can't believe Honda meant to assemble all the bikes like this. I also notice each of the two halves of the engine cases on the bottom has a "B" hand-written in blue ink. Between that "grafitti" and the silicone, I am beginning to think perhaps I bought a bike which was manufactured on a Monday or a Friday, if you catch my drift. Can any others in this community see evidence of grey silicone seepage on your engine case halves? I don't have my Helm service manual yet, but does anybody know if this engine has at least an oil strainer on the end of the oil pickup before it goes to the pump? Man, it better, if Honda used silicone on all of them, especially after seeing the post on the butched oil filter seal someone discovered during his first oil change.

 

[sendler]

Honda used no freaking gasket, just silcone all the way around

Sealer only without a gasket is the modern way, especially where the two pieces form something that is dimension critical like a bearing clearance. Except for the headgaskets which are three layer, a Mercedes Benz is generally sealed together throughout the drive train with no gaskets for the last 5 years. The fit and rigidity is better than gaskets and the modern sealers work great.

 

[flighttime]

Honda used no freaking gasket, just silcone all the way around, from the front of the case, near the base of the cylinder head, underneath, and back up the rear, above the starter motor and back to the rear of the cylinder head. There is excess silcone oozing out almost all the way around. I really cannot believe this was meant to be assembled like this!

As Sender says..
Normal practice these days, and after 25 odd years in the trade I wouldn't want to see it go back to gaskets. Nothing wrong with the correct sealer, and the machining is so good that it does not need anything else. I've even seen some new engines where they have no cylinder head gasket. The head is part of the block, with the valves etc inserted through the cylinder. No chance of a leak in the gasket there....

 

[Aufitt]

And the problem with this manufacturing is?

perhaps the OP would prefer and Old Triumph Bonnie with oilstains the driveway?

 

[Luke]

That Bonnevile was NOT leaking oil - it was marking it's territory.

 

[pricelister]

Yep. Honda doesn't know much about motors.

 

[250 Tom]

Goes to show how well these surfaces are machined.like to see Harly try that. They leak oil with a gasket

 

[somebody5788]

Sendler is right.

You can't torque down well when there is a gasket in the way because it makes the gasket less effective. This in turn leaves bolts that can come lose. In many cases they have started using copper inserts when using gaskets but even then the gasket doesn't have even pressure on it.

The solution? Sealant, it allows the bolts to be torqued like any metal to metal surface and seals better in most cases.

 

[BBRMotosports]

In this day in age they do not use case half gaskets on alot of engines .All my MX bikes were put together with anarobic sealer or a silicone from the factory. Doesnt mean anything about being cheap. If you ever had to rebuild it and say they used gaskets and you used aftermarket ones you might have shifting issues. I have seen it before to where the different thickness makes all the tolorances bigger and have had issues from it. Sealer is the way to go IMO. As far as a strainer I'm not sure if they do or not. I know my CRF's have them so I would imagine this bike would too.

 

[somebody5788]

I actually replaced my clutch housing cover because it was scratched and it does indeed have a strainer in the bottom of the engine. However there were no contaminants other then the normal shavings of metal left after the first 600 miles of break in. Even that was minimal to non existent.

http://www.partspitstop.com/pages/oemparts?aribrand=HOM#/Honda/CBR250R_2AC_%2811%29_MOTORCYCLE%2c_THA%2c_VIN%23_MLHMC411-B5000001/CRANKCASE/CBR250R-11-THA-2AC/2Y14KYJBKYJ4E1500A

Part number 5

 

[superanium]

This is how all modern engines have been assembled for years.

 

[Turbo DV8]

Thanks for all the replies. I've been enlightened that todays sealants "are not my father's silcone sealant!" Actually, my father probably used Indian Head gasket maker, but that dates me! I just picked up my service manual today, and indeed it specifies Honda Three Bond, which i know is not just "silcone." So, thanks again, and now I can sleep until I find something else to obsess over!