That Honda 929RRY *Issue* The 4 that became a twin.

[Bernster]

Let me be honest, much of what you have posted on this problem doesn't make sense or contradicts itself.....

You said early on that compression was fine yet it was also reported that cylinder 1 & 4 didn't have intake vacuum, they were actually at a pressure higher than atmosphere. You also report that the exhaust cam shaft was mistimed.

It would be physically impossible for a compression test, done correctly and using properly functioning equipment, to have NOT shown this by a massive difference in peak cumulative pressure on cylinders 1 & 4 when compared to 2 & 3.

You say that it doesn't fire up when you spray easy start into cylinders 1 & 4. Again, this points to a compression issue as the whole point of easy start is that it doesn't need a spark to ignite it when compressed in the normal 4 stroke cycle, it "diesels".

You need to stop thinking electrical and start thinking mechanical and go right back to basics. Get a proper compression and leak down test done.

Cheers for the assistance, it's appreciated. A few of the things posted I think were posted by other knowledgeable peeps and not me.

Don't shout, I'm not a mechanic, I work with pewter's but how can a timing effect both cylinders 1 and 4 when they're 180 degrees apart? Unless the timing was so very far out, which it wasn't.

Also what's the difference between acompression test’ which has already been undertaken and a leak down test’?

At the beginning I was suggesting that maybe it was a valve bent or stuck, (from the explosion) but many have suggested that this would be rare to effect 2 cylinders so far apart.

*Edit: What's the chances of a faulty Crank Position Sensor only locating positions 2 and 3?

[szrdave]

It's HISS, so you can't just swap em.

Just a quick note, the only two bits that are 'coded' together are the ECU and the chip in the key.

If you can borrow a matched ECU and key then wrap your existing key head in foil and use it to turn the ignition on, and put the borrowed key beside the antenna (just in front of the top yoke). This should hopefully fool the HISS.

[Bernster]

The compression test you say has been undertaken is worthless because it did not pick up the fact that the exhaust camshaft was mistimed meaning that some of the compression generated by the piston travelling up in the bore was being lost because the exhaust valves were opening early and as a result you were loosing compression on cylinder 1 & 4. Someone who knows what they are doing with a decent compression tester needs to redo the compression test properly. You need to look at the comparative compression readings between each cylinder and also the individual readings when compared to the quoted compression ratio or acceptable compression test values in the factory manual.

A compression test only measures the compression generated through several complete 4 stroke cycles by turning the engine over. A leak down test measures the capability of the combustion chamber to hold compression in a static state and tells you where any leaks are occurring - basically you pump compressed air into the cylinder through an adaptor screwed into the spark plug hole with all of the inlet and exhaust valves in the closed position and seal it of with a valve that has a pressure gauge upstream of the valve. You observe how much pressure drop there is and depending on where the air is escaping from (out of the exhaust means exhaust valves, out of the TB's means inlet valves etc etc) you know where the problem is.

Piston's 1 & 4 are in phase - they are at TDC at exactly the same time.

There's little or no chance of a faulty Crank position sensor causing your symptoms - the CPS merely tells the ECU where the crank is within one rotation and the ECU then works out what to do with the info, if 2 & 3 are running fine the CPS is fine.

I struggle to believe it when you say that a proper timing test has been done - this is beyond the wit of most main dealers or mechanics in my experience and falls within the realms of engine builders/tuners (main dealers and mechanics just don't have the time and equipment to undertake the work necessary to remove the ignition cover to access the end of the crank, fit a degree wheel to the crank and pointer to the engine cases, fit a long probe DTI and find TDC, zero the degree wheel, fit the DTI on the cam lobe profile, turn over the crank by hand and measure the deflection and lift and compare it with the specs for the cams relative to the crank position).

Gotchya, I'll get my mate round with the compressor and the skills ,(Nige) round with his kit to check bound inlet and outlet. Cheers chap.

[bigkev]

I bought a FZ750 years ago that had been front ended for a bit of repair and sell on job, but the first time I rode it up to the redline it shat itself , upon inspection I found that the exhaust cam was one tooth out and the valves had clouted the pistons, not badly but enough for it to run like shit, so I find it hard to believe that you could have a cam out by TWO teeth and not damaged something. I'm with millemille and would go for a proper compression/leak test first.

Good luck

[Bernster]

It was ridden for approximately 20 miles on two cylinders, so if anything did happen it didn't stop cylinders 2 and 3 stop working It's either a mechanical issue and a hard engine or a wuss. My mates coming round tonight with the compressor in his van and The Master that is Nige is coming round to prod at stuff. I'll make tea and ask silly questions

[ronenige]

Wellllll , went round last night for a quick shuftie with a couple of tools and a compressor . locking the crank at TDC on the comp stroke and feeding compressed air in showed only a very small amount of air leaking past the valves , not enough to cause the problem but ALL the cylinders were losing air into the crankcase , with what tools we had and working by torchlight we couldn't really tell if it was leaking between one cylinder and another but i'm thinking the top has got to come off for further investigation ;

cyl no

1 ind comp ign ex

2 comp ign ex ind

3 ex ind comp ign

4 ign ex ind comp

with a 1342 firing order , if the head gasket is leaking between 1+2 and 3+4 you can hopefully see that when it fires on cyl's 2 and 3 it would leak into the adjacent cylinders when they are on the compression stroke which could cause the pressure in the inlet manifolds , just got to find a bit of time soon to take the bike off the engine then whip the head off , just seems a bit unusual that both sides go at once , we did do another compression test and were getting around 200psi but it only takes a very small leak between cylinders to cock thing up and there is a bit more than 200 psi when the cylinder fires .

That , boy's and girls is where it's at as of now

[Bernster]

Provisionally sold!

[Superdunc]

Wellllll , went round last night for a quick shuftie with a couple of tools and a compressor . locking the crank at TDC on the comp stroke and feeding compressed air in showed only a very small amount of air leaking past the valves , not enough to cause the problem but ALL the cylinders were losing air into the crankcase , with what tools we had and working by torchlight we couldn't really tell if it was leaking between one cylinder and another but i'm thinking the top has got to come off for further investigation ;

cyl no

1 ind comp ign ex

2 comp ign ex ind

3 ex ind comp ign

4 ign ex ind comp

with a 1342 firing order , if the head gasket is leaking between 1+2 and 3+4 you can hopefully see that when it fires on cyl's 2 and 3 it would leak into the adjacent cylinders when they are on the compression stroke which could cause the pressure in the inlet manifolds , just got to find a bit of time soon to take the bike off the engine then whip the head off , just seems a bit unusual that both sides go at once , we did do another compression test and were getting around 200psi but it only takes a very small leak between cylinders to cock thing up and there is a bit more than 200 psi when the cylinder fires .

That , boy's and girls is where it's at as of now

If you've got a compression leak between two cylinders you will hear the air escaping out of the spark plug hole (asumming no plugs are fitted) on the adjacent cylinder when you do a leak down test.

[weaver]

Out of interest did you ever get to the bottom of the problem and get it fixed?

[Bernster]

Out of interest did you ever get to the bottom of the problem and get it fixed?

It was 'sold off' to a bloke that informs me he'll email me once he's found the root of the problem and fixed. However based on some of the questions he was asking me and answering himself made me wonder if he would fair any better.

[weaver]

Oh well at least it is his problem now and not yours. I'd still be interested to find out what the root cause was but as you say it sounds unlikely that you/we ever will!

[Bernster]

Oh well at least it is his problem now and not yours. I'd still be interested to find out what the root cause was but as you say it sounds unlikely that you/we ever will!

The great Nige and a few others are intrigued as to what the final solution would be, if he does ever 'fess-up' I'll update it on here. I lost a pile of wedge but learned something, I have an allergy to 'Onda's

[weaver]

Learning anything about the inner workings of machinery always seems to be expensive in my experience. Usually because you are having to look at it because something has gone wrong or you are trying to make it go faster which inevitably leads to something going wrong