Value adjustments? - Motorcycle-Journal Forums

zleviticus · 07-08-2004, 12:57 PM

I am a car guy and just gettign into motorcycles... I keep reading about value adjustments on cycles and that it should be done every x miles. Are the lifters in a bike mechanical lifters and not hydralic? Would a DOHC bike have lifters?

**87gsxrnut** · 07-08-2004, 01:25 PM

Overhead cams have rocker arms.

- Nut

zleviticus · 07-08-2004, 01:36 PM

But I thought that (at least on a car) an overhead cam eliminates the need for rockes since the cam and the valves are connected together (in a loose sense) or in other words the tapet that rests on the cam is not connected to a push rod but is attached directly to the valves.. is this not the case on a bike?

<Addition>
Ok I found a spec of the cam and such and see the rockers... what a waste of fricton though. i would think that is would be better to eliminate moving parts for more power.

**87gsxrnut** · 07-08-2004, 02:26 PM

How would you adjust the valves then?

- Nut

zleviticus · 07-08-2004, 02:40 PM

that was my point.. I would not think a motorcycle with a DOHC would need to have the valve adjusted. A car with a DOHC does not... as mentioned earlier their are not rocker arms on the DOHC engines I have worked on that is why I thought it was strange to have to do a valve adjustment on a newer motorcycle.. The last time I have had to do a valve adjust is when i rebuil thte engine in my camaro.. or periodically on my 72 super beetle when I owned it.. now iwth hydralic lifters and DOHC i did no tthink you would have to do that.. but I guess I was wrong.. (was not the first time

)

The Chad · 07-10-2004, 04:00 AM

be careful on what you think you may know. Cars that have either single or dual ohc can be direct acting or indirect acting. All non adjustable ohc motors use a hydrolic lifter. Some in combination with a rocker arm, some without rockers. Some adjustable ohc motors only use a rocker arm with no lifter and others use both rocker arm and lifter, and others yet use only a lifter. the adjustable type use a shim system or set screw and lock nut to take up clearances. Finally the reason they went to ohc motors is so that you have less reciprocating mass ie pushrods.

07-08-2004, 12:57 PM	#1 (permalink)
zleviticus Ditch Magnet Joined: Mar 2004 Location: Lexington, Ky Posts: 165	Value adjustments? I am a car guy and just gettign into motorcycles... I keep reading about value adjustments on cycles and that it should be done every x miles. Are the lifters in a bike mechanical lifters and not hydralic? Would a DOHC bike have lifters?

07-10-2004, 04:00 AM	#6 (permalink)
The Chad Site Wrench Head Joined: Nov 2003 Bike: crashed Location: Duncan B.C. Posts: 635	be careful on what you think you may know. Cars that have either single or dual ohc can be direct acting or indirect acting. All non adjustable ohc motors use a hydrolic lifter. Some in combination with a rocker arm, some without rockers. Some adjustable ohc motors only use a rocker arm with no lifter and others use both rocker arm and lifter, and others yet use only a lifter. the adjustable type use a shim system or set screw and lock nut to take up clearances. Finally the reason they went to ohc motors is so that you have less reciprocating mass ie pushrods. __________________ A truly wise man asks more questions than he answers, I think I must be retarted

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07-08-2004, 01:25 PM	#2 (permalink)
87gsxrnut Ho Dog Joined: Dec 2003 Bike: 867-5309 Location: Terror Lake Posts: 4,224	Overhead cams have rocker arms. - Nut

07-08-2004, 01:36 PM	#3 (permalink)
zleviticus Ditch Magnet Joined: Mar 2004 Location: Lexington, Ky Posts: 165	But I thought that (at least on a car) an overhead cam eliminates the need for rockes since the cam and the valves are connected together (in a loose sense) or in other words the tapet that rests on the cam is not connected to a push rod but is attached directly to the valves.. is this not the case on a bike? <Addition> Ok I found a spec of the cam and such and see the rockers... what a waste of fricton though. i would think that is would be better to eliminate moving parts for more power.

07-08-2004, 02:26 PM	#4 (permalink)
87gsxrnut Ho Dog Joined: Dec 2003 Bike: 867-5309 Location: Terror Lake Posts: 4,224	How would you adjust the valves then? - Nut

07-08-2004, 02:40 PM	#5 (permalink)
zleviticus Ditch Magnet Joined: Mar 2004 Location: Lexington, Ky Posts: 165	that was my point.. I would not think a motorcycle with a DOHC would need to have the valve adjusted. A car with a DOHC does not... as mentioned earlier their are not rocker arms on the DOHC engines I have worked on that is why I thought it was strange to have to do a valve adjustment on a newer motorcycle.. The last time I have had to do a valve adjust is when i rebuil thte engine in my camaro.. or periodically on my 72 super beetle when I owned it.. now iwth hydralic lifters and DOHC i did no tthink you would have to do that.. but I guess I was wrong.. (was not the first time )

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