V1000G5 issues

[Mor]

Hi,
My new(to me) 1984 V1000G5 is losing power at high speed over 5500rpm and blowing oil out of the breather. When I am cruising at ~4500rpm and up to that point all is well with the bike. But if I give it wide open throttle it bogs down and blows oil, it comes out the airbox drain tube which today happened to drip onto the exhaust and create a massive cloud of smoke.
Going to do a compression test this week but wanted to hear your opinions/thoughts on this.
The bike has had new pistons and rings, new valves and guides. Electronic ignition.
Oil level is right in the middle between the upper and lower marks.
It has the ball valve in the top breather tube and the flapper in the airbox has been removed.
New oil and air filters installed.
After sustained high speed riding there's a good amount of oil dripping from the joint of the airbox with the metal clamps and springs and coming out of the drain tube.
Definitely seems as though the crankcase is building up high pressure at high rpm.
Appreciate any replies to this, thanks.

[guzzisteve]

Check the ball valve in large tube, it may be stuck. My 86 Cal2 stuck & blew my rear main.

[Frenchfrog]

Hi,
My new(to me) 1984 V1000G5 is losing power at high speed over 5500rpm and blowing oil out of the breather. When I am cruising at ~4500rpm and up to that point all is well with the bike. But if I give it wide open throttle it bogs down and blows oil, it comes out the airbox drain tube which today happened to drip onto the exhaust and create a massive cloud of smoke.
Going to do a compression test this week but wanted to hear your opinions/thoughts on this.
The bike has had new pistons and rings, new valves and guides. Electronic ignition.
Oil level is right in the middle between the upper and lower marks.
It has the ball valve in the top breather tube and the flapper in the airbox has been removed.
New oil and air filters installed.
After sustained high speed riding there's a good amount of oil dripping from the joint of the airbox with the metal clamps and springs and coming out of the drain tube.
Definitely seems as though the crankcase is building up high pressure at high rpm.
Appreciate any replies to this, thanks.

How many miles since the rebuild? Sounds like the rings are not bedded in yet...or maybe the oil control ring is upside down ?

[Mor]

Hi Steve,
The ball is free in there. Could the oil be coming from one of the other breather hoses?
Frenchfrog, I don't know the mileage since the rebuild but I don't think it was used much since. I was wondering about the oil control ring too, a compression test might not tell me if that's the cause. I'll get a leak down tester in the meantime.
How long would it take for rings to bed in? I've covered over 1000km so far.
Maybe I have 2 unrelated problems..
Thanks

[Antietam Classic Cycle]

Is there a sump spacer fitted? It goes between the engine oil pan/sump and engine block. If not, I would install one, or a deeper sump from an EV era engine. The extra volume can make a huge difference.

[Mor]

No sump spacer fitted. I was hoping to take a break from ordering parts for this bike. I bought it, rode ~200km and the clutch went. Turns out it had a RAM clutch fitted so I had to order a used clutch and new plates to bring it back to standard. Then after fitting the clutch it started leaking oil from the bell housing slot, I didn't see any oil in there when I did the clutch. I'm thinking the leak might also be caused by excess crankcase pressure.
I'll do a compression test tonight and report back.

[blackcat]

No sump spacer fitted. I was hoping to take a break from ordering parts for this bike. I bought it, rode ~200km and the clutch went. Turns out it had a RAM clutch fitted so I had to order a used clutch and new plates to bring it back to standard. Then after fitting the clutch it started leaking oil from the bell housing slot, I didn't see any oil in there when I did the clutch. I'm thinking the leak might also be caused by excess crankcase pressure.
I'll do a compression test tonight and report back.

Check the hose clamps on the breather box as they could be leaking and the oil is draining through the housing slot.

[Mor]

Those clamps are all tight, just had them off to inspect the box and change air filter.
Compression test results: 170 psi rhs and 160 psi lhs. Will check valve clearances when it cools down.
Thanks for all the replies👍

[guzzisteve]

Is there a sump spacer fitted? It goes between the engine oil pan/sump and engine block. If not, I would install one, or a deeper sump from an EV era engine. The extra volume can make a huge difference.

If all checks out like it is, it would be volume of air.  Reason they put pan spacers on them. Like Charley says.

[Mor]

Valve clearances 0.15mm intake and 0.2mm exhaust.
I’ll order the spacer.

[guzzisteve]

There is also filter spacers that put filter outside and are same thickness.

[moto]

I agree that lack of crankcase capacity could lead to problems with the breather. But I don't think it would reduce power at high RPM. After all, the energy lost to pumping the crankcase up on each stroke is mostly regained on the subsequent 180° if the breather isn't working. I would check the timing, both of the spark and the valves. Have you checked the valves opening and closing points against the marks on the flywheel. Have you checked that TDC as marked on the flywheel is really TDC? Those things could affect power at higher speeds.

Have you checked the advance of the ignition against known-good marks?

Someone could've put your bike together wrong, since you just got it. Unless somebody steps in and says that the 1000 cc engines never worked well above 5500 RPM, I'm not convinced that it is a crankcase capacity problem, since they all shared the same crankcase from the factory.

[Tony F]

Hi.

You say the bike has had new pistons and rings, is that new cylinders (Gilardoni or the like), or rebored standard iron cylinders, or new pistons and rings in old standard bores? If the latter new pistons and/or rings wont completely stop blowby. Is the rest of the engine stock?

What type of breather box is the bike running? Is it the LeMans 1/11 type? The bigger Agostini breather box is another option here.

In addition to a sump extension, which has already been mentioned, a windage plate may help.

[Mor]

Sump spacer is on the way.
I also ordered a set of plugs, they tested ok but I've had plugs that tested fine out of the bike and didn't work properly when installed.
The flywheel marks lined up when doing the valve clearances. I'll check the timing with a strobe light over the weekend and report back.
Looks like the standard breather box to me, I'll try to get a photo of it and post it here.
I don't know if the barrels were replaced, I'll have a close look later. The compression test was reassuring.

[Don G]

Best do a leak down test, compression test may read good but if there is excess oil in the cylinders compression test reads good. You may be surprised at the results of a leak down test.  DonG

[John A]

If the breather box has an internal spring loaded valve, it doesn’t need a ball valve. It should be one or the other not both. The ball valve has been updated with a square hole on the upstream end instead of a round hole so it can not completely close itself off. It should come alive at 5K rpm and up to redline. Third gear at 5500 rpm is great for mountain roads and passing.

[Antietam Classic Cycle]

If the breather box has an internal spring loaded valve, it doesn’t need a ball valve. It should be one or the other not both.

It has the ball valve in the top breather tube and the flapper in the airbox has been removed.

[John A]

Thanks, Charlie. I looked for that before I posted but didn’t see it.

[Groover]

Subscribing. Was going to say the ball/valve on top of the crankcase, but you checked that.

[Mor]

So, decided to check the timing. The “D” mark should be right on the mark in the window when the led on the electronic ignition goes off(TDC rhs). But the D was up near the top of the window at that point so the ignition must have been retarded by a few degrees. Adjusted it so the led turns off just when the D is on the mark and took it for a quick blast. Much improved performance and I didn’t get any oil coming out of the breather drain tube. I only got out for ~60km and no sustained high speed stuff but seems good. I’ll still fit the sump spacer when it arrives and get out for a good long ride and report back.

[Don G]

There are 3 timing marks on the flywheel, TDC with an S or D, a static timing mark above that a little bit and way above that a full advance timing mark and you check that at about 6000 RPM. You also may see an arrow above the full advance mark, disregard that.  DonG

[Antietam Classic Cycle]

The marks on the flywheel can sometimes be off considerably, best to use a piston stop and degree wheel to find true TDC and see if the marks are correct. 

[Tom H]

I just worked on a bike with a flywheel that was off about 10 deg. What the heck??? So much for QC??

Tom

[Antietam Classic Cycle]

I just worked on a bike with a flywheel that was off about 10 deg. What the heck??? So much for QC??

Tom

Mark was telling me about that one! 

[moto]

Timing was my guess.

When I first got my T3, I spent some time checking the flywheel marks, just to be sure.

Charlie's recommendation to use a piston stop is the best bet, but I used a straw stuck in the right spark plug hole to make sure it reached its greatest height at the TDC mark, D, for that cylinder. The spacing of the flywheel teeth is 3.75°, point to point, so observing them through the window gives a pretty good idea of where TDC is.

You said your bike has an electronic ignition, but you didn't indicate which one, or whether you had checked its timing at full advance with a stroboscopic timing light. Getting the timing right at full advance is crucial for enjoying the motor at high RPM, where it sings.

I assume you have the Haynes manual, but here are some relevant passages anyway.









And here are some notes about the flywheel teeth:

[moto]

A second note, from 2002, recorded my actual static and full advance degrees after setting the full advance with a stroboscope. Note that the static timing is different from the spec in the manuals (the "Spec" columns) as is consistent with Dave Richardson's comments in Guzziology.





This shows how important it is to set the timing dynamically with a stroboscope at 6000 RPM.

[John A]

The marks on the flywheel can sometimes be off considerably, best to use a piston stop and degree wheel to find true TDC and see if the marks are correct.

Yes, I’ve been saying this for thirty years. In relation to each other the marks are fine. In relation to the engine, I have not seen one that is accurate. On an engine that you use the marks for timing ignition, it is worthwhile .

[moto]

Yes, I’ve been saying this for thirty years. In relation to each other the marks are fine. In relation to the engine, I have not seen one that is accurate. On an engine that you use the marks for timing ignition, it is worthwhile .

Surprising! How many older Guzzi big blocks have you checked? How many degrees were they typically off?

EDIT: Depending on your answers, I may have to mount a degree wheel and recheck.

[John A]

Surprising! How many older Guzzi big blocks have you checked? How many degrees were they typically off?

EDIT: Depending on your answers, I may have to mount a degree wheel and recheck.

I bought a new Bassa in ‘99. It had ten miles on it and I changed the cam to a Norris S , timed in at two degrees advanced on the intake centerline. Since I had a degree wheel on it , I checked the TDC mark which was about 3/8” off.  I do the cam change at low miles so I don’t have to replace the lifters. It was the same thing on a previous Cal2. Before that it was T’s and T3’s, none of which I bought new. I think most of those were around 1/8” to 1/4” off.

[moto]

I bought a new Bassa in ‘99. It had ten miles on it and I changed the cam to a Norris S , timed in at two degrees advanced on the intake centerline. Since I had a degree wheel on it , I checked the TDC mark which was about 3/8” off.  I do the cam change at low miles so I don’t have to replace the lifters. It was the same thing on a previous Cal2. Before that it was T’s and T3’s, none of which I bought new. I think most of those were around 1/8” to 1/4” off.

If you used a 7" degree wheel then 1/8, 1/4 and 3/8 inches amount to 2, 4 and 6 degrees, respectively (2.046, 4.093 and 6.139). 4 and 6 are concerning. Though the OP should at least do the straw procedure I mentioned before, the advice to use a degree wheel is better.

It seems like the T's and T3's were better calibrated, so I hope mine is OK. But I may just get a degree wheel and piston stop and check it this summer. If so, I'll add my result to the end of this thread, for posterity. Thanks for providing the details.

Moto