Locked up engine

[Harry]

Hi, I rode today and my 02 EC300 locked up after about 40km, thought it was seized, I started it shortly afterwards and engine makes a horrible grinding / crunching sound ? I shut it down straight away!

I pulled the head off and and the bore and piston show no signs of distress, plug is a dark tan colour and radiator was full.

Any pointers before I dig deeper? - note bike may be 2002 model but I have owned it from new and it is still on original chain and sprockets, which are still in good order, so hours are pretty low.

Thanks in advance,

Oldmog

 

[PEB]

Transmission. My 02 blew up 40 miles from the truck. It made for a long long day

 

[jhendr3702]

Transmission. My 02 blew up 40 miles from the truck. It made for a long long day

My thoghts also witnessed a buddies do the same thing zero notice before hand

 

[Harry]

Any thoughts on what part of the transmission?

 

[PEB]

2nd gear went on mine taking out a couple others with it. Full rebuild time or buy a replacement.

 

[Dockillemall]

Right side main crank bering would be my guess.

 

[Tigger52]

MIne's done this twice - on both occasions it was the nut on the right hand side of the crank which came loose.
Just strip it, clean the threads well and use loctite and let it set up before re filling it with oil - mine's been fine since the scond time!

 

[Harry]

Hi To All,

Thought I would share my findings. It was the main crank bearings that failed. Both were very rough and corroded as were the big end, small end and associated bearings.

This bike has been stored more than it has been ridden, so I can only assume condensation has caused the internal corrosion. Any Ideas on preventing this again would be appreciated?

So now it has all new internals and I deceided to measure the squish, and I am shocked to say it measures 2,5mm. This is with a new Woessner piston and 1 x 0.5mm base gasket. The piston is also higher than the base of the transfer ports by 1mm and higher than the base of the exhaust port by ?2mm.

Any thoughts on the above would be appreciated, as now would be the time to make any reccomended improvements.

Thanks - Harry

 

[Jakobi]

Hmm.. If its all back together then theres not alot you can do bar taking it all back apart..

I'd have personally set the exhaust port flush with piston at bdc. Even though thats 2mm of gasket stack (or had a spacer made up). Then you can look at getting the squish measured and reduced, and with that much you'd need a reshape of the bowl aswell.

I'd ride it as is until next time you need to venture in for some work.. Then have the battle plan ready.

 

[Harry]

The motor is in the bench, so now is the time to strike.

 

[twowheels]

Its hard to bet against Jakobi, but if you're ready and able he's given you the plan of attack.

 

[Harry]

Update - I have machined 1mm of the head, this has reduced the Squish from 2.5 to 1.5mm.
This has changed the Uncorrected Compression Ratio from 10.7:1 to 12.2:1 (calculated) I plan to use 98 octane and see how it performs. I can always reshape the dome to lower the compression ratio.

Any opinions would be appreciated on 12.2:1 using 98 octane?

Corrected Compression Ratio (calculated) increased from 7.33:1 to 8.32:1

Thanks - Harry

 

[Jakobi]

Woaaaah number crunching on a friday night@! I'm not very good on the numbers side of things but I'd say you will be fine with it.

When I did my head I went from stock to S3 High high (black) insert. It essentially did the same thing as shaving 1.0mm off. I've experienced no issues running 98

 

[Harry]

Thanks for the feedback Jakobi.

I will report back when I have had a chance to complete my Showa 47mm fork swap.

Lots of projects too little time.

 

[Jakobi]

This thread needs pics Harry!

 

[Harry]

Corroded engine internals

 

[Harry]

Crank truing

 

[Harry]

Custom steering stem to suit RM250K5 Triple clamps, 22.5mm offset. I Machined this from a piece of 7075-T6 billet aluminium.

 

[Harry]

Showa 47mm forks (RMZ250K7) fitted to 02 EC300 using all the OEM bearings and seals. I am awaiting a bush and seal kit to rebuild the forks.

Any tips on Showa forks would be appreciated - fork oil, quantity etc.

 

[Harry]

Head being machined, I put the rubber bands on to stop it resonating