Hitchcocks Forum

Hi All,

I started my friends TT750 today for the first time since I completely rebuilt the engine. All went well and it didn't take long for the engine to fire up. I only run it for a very short time but it sounded really good and the electronic ignition performed perfectly.

During the rebuild I have fed the rockers from the right hand half of the crank case using a 'Y' feed pipe and blanked off the left half oil feed. Before starting I removed the rocker feed bolts and squirted some oil in to aid first start. My question is how long will it take to get the oil circulated up to the rockers as it looks like I have no oil in the feed pipes. I have only run it a few times for very short periods as I don't want to damage anything due to lack of oil but on the other hand do I need to let it run to get the oil there? I am caught in two minds as to what to do.

Can anyone share their experience and advise how long it should take to get oil to the rockers?
With the engine not running I did loosen the oil feed bolt on the side of the timing case and lots of oil came out so I am sure the oil pumps are working.

Thanks
Stuart

If it's the same as the bullets, the pumps send oil to the crank first, which drains down into the cases, then the scavenge pump picks up from there and sends it to the rockers. Did you put some oil into the cases on re build? This would have gone to the rockers quicker. I would advise, if you are sure everything is as should be, just start it and let it tick over for a while with the rocker feed loose and see if it eventualy seeps oil.

Thanks for the reply.

I put oil in the main tank obviously but not in the return tank.
I thought the feed pump pumped oil to the crank and the rockers, when this oil goes to the bottom of the engine below the crank the return pump then pumps the oil back in to the main tank.
Should I put some oil in to the bottom of the crank? If so how is it best to do this? via the rocker covers?

If you lubricated as you should while reassembling you should be OK for a minute or two until the oil gets round. If you are worried, take the rocker feed pipe off and squirt some in directly. People overestimate the amount of oil required by bearings for lubrication, especially on tickover. Most of the oil flow is for cooling purposes.

Stuart, I apologise if I missled you, for a start I'm not sure what a"TT750" is, ( Interceptor, Triumph?) The oil system is obviously different to the Bullets. As for "main tank and return tank", sureley there is only one tank, which feeds the engine, and receives the return oil?

No problem Nettshubby, I should have put more detail of the bike in the first place.
It is an Interceptor Mk1a TT 750.
There is a flow and return pump. The flow takes oil from the main tank and this is pumped to the crank and the rockers. This oil is then collected in an area seperate to the main tank under the crank shaft. This oil is then pumped by the return pump back in to the main tank.

Thanks for all the replies. I think I'm going to squirt loads of oil in to the rockers and then let it run a bit longer until I get oil to the rocker feed pipes.

Stuart - You are likely having a priming problem with the supply oil pump. The pump design is an oscillating plunger pump and uses the “backside” of the piston to supply oil to the rockers. Given time the pump should prime and all is well. You are spot on in pre-oiling your assembly, the boundary lubrication should prevent damage to the rockers and shafts while the pump primes. I avoid this problem after overhaul by slowly filling the supply sump while the engine is on the bench. I have the supply pump cover removed and have previously positioned the oscillating pump body to fully counter-clockwise by slowly cranking the motor. This opens the pump suction port to the sump and allows the supply line to purge all air from the suction strainer and supply line as I add oil to the sump. Yes, can be a bit messy if not done proper and quickly place the cover! There are other problem areas which COULD affect oil delivery to your rockers: 1) The rocker line relief valve is stuck open. 2)You forgot to replace the plug behind and above the timing gear. 3) Your right cylinder base gasket is allowing oil to vent to the case. 4)Your timing cover gasket is allowing oil to escape or worse yet air to be drawn into the supply port, new gaskets are mandatory! A few things to consider prior to first start (next time!) — The purchase of a new oil pump and piston from Hitchcocks is money well spent! Worn stock pumps are at best a sorry lot, and slight piston to body wear will greatly affect priming your system. Always pour 200 cc of oil down ONE of the intake AND exhaust tappet covers, this fills the cam tunnels thus lubricating the cams, also providing lubrication to the pump drive worm and timing chain. I fabricated a fitting which I place into a modified crank oil supply plug while on the bench to pre-lube the crank, thus filling the sludge trap. By slightly opening the oil filter cover while pumping oil to the crank I also purge trapped air from the filter housing. All these steps ensure proper and timely oiling of your new parts. Best of luck in your project - be safe!

Stuart - Forgot a few things! 1) Always lap the pump body to the timing case! 2) I lightly coat the pump drive shaft with a very light body grease as I load it into the timing case, this aids in providing first lubrication and prevents air leaks into the pump cavity during priming. Be certain to wipe any excess grease from the shaft ends after assembly. 3) NEVER use grease on the oscillating pump body, it can plug the small ports and inhibit proper pump priming. A good pre-lubrication with your engine oil is sufficient.