MB100 development

[Hilleye]

Crank and conrod.


Note the patch of rust. I'm thinking after reading F5Dave's post that maybe the bike fell victim to being parked up in Upper Hutt for 18 months without being run. The result being the main and big end bearings have corroded and the two days of practice prior to the BoB was enough to flog them out. Bearing on crankshaft (Mag Main?) had very, very small amount of play in it. One that sits in the case (Drive main?) has quite a significant amount.

Conrod play.

Approx 2mm at top. Questions for those that know. Is this excessive? Does it indicate the bearing is worn? Will the conrod need replacing or just the bearing?

[Yow Ling]

Approx 2mm at top. Questions for those that know. Is this excessive? Does it indicate the bearing is worn? Will the conrod need replacing or just the bearing?

the side play in the small end no concern as the rod is centralised on the crank.
You just buy a rod kit, it has a new rod , big end bearing, crankpin and thrust washers. buy a new small end and new mains. that is what you need
If you send me the crank I will fit all the parts

[koba]

A new rod should also have oil slots instead of holes and the newer big end bearings are supposed to be better quality than original ones.

That Inlet port looks horrible.

I would guess that head leaks too, the way to fix that is to O-ring it or machine the head and barrel to have a spigot fit that is then lapped. Like an old Volkswagen.

[Hilleye]

I would guess that head leaks too, the way to fix that is to O-ring it or machine the head and barrel to have a spigot fit that is then lapped. Like an old Volkswagen.

Sorry, with that photo the metal gasket is actually sitting on top. Didn't realise it was there till I put the head down again after taking the photo and it slipped off. Can redo them if you need to see the detail underneath.

[Hilleye]

You just buy a rod kit, it has a new rod , big end bearing, crankpin and thrust washers. buy a new small end and new mains. that is what you need.

Just go to Honda dealer or is there somewhere else I should try?

[TZ350]

Just go to Honda dealer or is there somewhere else I should try?

Conrod kit, check with them to see if its slotted. http://www.trademe.co.nz/motors/moto...-415302675.htm

[koba]

Sorry, with that photo the metal gasket is actually sitting on top. Didn't realise it was there till I put the head down again after taking the photo and it slipped off. Can redo them if you need to see the detail underneath.

You will see signs of leakage if it is. If you look at it carefully you will know it when you see it.

EDIT: looks like it is leaking out towards the head mount, hard to say from here though, have a good look and work out why that side is all mucky.

That rod kit is a 'long (brand) rod'. The one I bought from the same place was slotted, even though when I asked he said it wasn't.
Dave had one snap ages ago so can't be sure about quality but I bought one...

[Hilleye]

You will see signs of leakage if it is. If you look at it carefully you will know it when you see it.

EDIT: looks like it is leaking out towards the head mount, hard to say from here though, have a good look and work out why that side is all mucky.

I think it's only mucky because it had been sitting on the bench with the remants of the gearbox oil. Some just got smeared on it when I picked it up. I will check for leaks though.

[Hilleye]

Conrod kit, check with them to see if its slotted. http://www.trademe.co.nz/motors/moto...-415302675.htm

Thank you. Much appreciated.

[F5 Dave]

The guys are right, anything that sits around can be suspect if not stored in oil.

My long rod in the MB50 snapped, but that can also be caused by over loose side clearance (I learned from the excellent Eric Gorr book), so the jury's out on long brand rods, however I do know from a mate in the bike biz that they used to do a lot of farm bikes with long rodkits & they'd die again until they started to throw the bearing away & use a genuine one.

As Koba states, that rod is the original Honda one from the 80s. New parts all round & you'll be set for years.

[husaberg]

The guys are right, anything that sits around can be suspect if not stored in oil.

My long rod in the MB50 snapped, but that can also be caused by over loose side clearance (I learned from the excellent Eric Gorr book), so the jury's out on long brand rods, however I do know from a mate in the bike biz that they used to do a lot of farm bikes with long rodkits & they'd die again until they started to throw the bearing away & use a genuine one.

As Koba states, that rod is the original Honda one from the 80s. New parts all round & you'll be set for years.

The rod that i replaced out of my h100 was the slotted style I assume it was std
Maybe its another example of the subtle differences between these engines.
The H100 followed the Mb100 but was a for the most part less racy design points ignition and milder port timing etc.
Assuming the Honda rods are still available unless a higher spec legal one can be found I would stick with a Genuine one.

Out of interest what was Speedpros one in his avatar it was obviously not brittle.

[koba]

The rod that i replaced out of my h100 was the slotted style I assume it was std
Maybe its another example of the subtle differences between these engines.
The H100 followed the Mb100 but was a for the most part less racy design points ignition and milder port timing etc.
Assuming the Honda rods are still available unless a higher spec legal one can be found I would stick with a Genuine one.

Out of interest what was Speedpros one in his avatar it was obviously not brittle.

The genuine replacement rods are slotted. The MB originals just have holes.

[dangerous]

Just go to Honda dealer or is there somewhere else I should try?

Its a farking shame TonyB's Motoequip failed due to a hot shot up north, he could have suplyed piston and rod kits of qualaty at decent prices...


And listen to YL below, I practely learnt every thing I know about strokers from him... pitty I aint a very good listener

the side play in the small end no concern as the rod is centralised on the crank.
You just buy a rod kit, it has a new rod , big end bearing, crankpin and thrust washers. buy a new small end and new mains. that is what you need
If you send me the crank I will fit all the parts

[F5 Dave]

Koba's full of it. good information I mean.

I suspect they just evolved the rods & that became std as Honda won't be making them themselves. I've seen one slot at the bottom & a slot either side as well.

The H100A & H100S are a little different, the S has points, not sure about A.

[husaberg]

The H100A & H100S are a little different, the S has points, not sure about A.

I said that above Dave
In front of me is a std Gen H100s Rod.
It has slots either side at big end and two holes at the top.
At 11 and 1 o'clock

I do note the bearings are colour coded i will post the specs. H100Sd

The observant amongst you will note the 360 centre code (Model) on the thrust washers on the big end.The 360 code refers to the Cr125m very similar to the Mt125R which is very in design detail like a lot of other Hondas.