Topic: Anyone know the #4 intake cam lobe proper position for BDC?

[juntjoo]

I'd rather not have to take off the head cover to check timing. I'm using #4 intake at BDC because the lobe is up to be able to use to measure. Before I put the head cover on it looked close enough but the marks never lined up perfectly before so I never quite knew.

I've got spark and fuel and with the aid of carb spray it started for a bit.

How obvious would one tooth off on the timing be? Would it start at all?

Anyone ever checked using the lobe position on #4?

Everything else was on point before I just last took it apart to replace the head.

[dave500]

only way to check it in such an arse about way would be to use a dial indicator and know the specs,easiest way would be to compare it to another motor,just pull the cover and do it right,the timing should've been checked when the cover was off,having set up the cam and chain rotate the engine and check it again.

[juntjoo]

I guess I wouldn't have 90psi(kinda low but it's what I've always had) of compression if it was a tooth off right? Is that a good way to check cam timing without removing the head cover?

[Scott S]

 Why do you insist on doing everything differently?
 There are manuals written with the proper procedures to do all this, you know?

[dave500]

no,the compression might not vary much,bring number 1 to tdc compression,number 4 lobes should be sort of up and both level sort of at an even amount.

when the cam is timed slot forward and level as per the book your actually setting it at #4 compression,both lobes are down and #1 is at overlap,visa versa if you time that slot rearwards,with your finger over the plug hole on #1 feel the compression coming up watching the 1/4 T mark and stop it there,by rights the slot should be rearwards and both #4 lobes upwards on overlap.

[juntjoo]

only way to check it in such an arse about way would be to use a dial indicator and know the specs,easiest way would be to compare it to another motor,just pull the cover and do it right,the timing should've been checked when the cover was off,having set up the cam and chain rotate the engine and check it again.

Well I just did do the timing before putting the cover on but I'm never quite 100% sure if it's right. The three marks, cam, crank and cam sprocket never seem to all match up perfect but I think I've been lucky so far as the bike has run pretty good. So I wonder

1)if it's a tooth off would it run at all? Also as in my previous post,

2)would you even have compression?

Also I imagine the lobe position to be a precise indicator, essentially like the marker on the end of the cam shaft since it's part of the same part, but can be seen without having to take the cover off. I don't see how that's "arse about" at all.

But I guess most just get it right before putting the cover on. And I probably did, but I'll say last couple times I didn't see the sprocket marks totally horizontal, but on a slight angle, yet the cam mark at the end was more horizontal. So those two marks basically fixed together have kinda thrown me off. I'm 85% sure it's right but before going back in there I'd feel better knowing the answer to my two questions above if you(or anyone) happen to know.

[juntjoo]

Why do you insist on doing everything differently?
 There are manuals written with the proper procedures to do all this, you know?

The sprocket and shaft end marks don't seem to line up perfect if I recall correctly. Reality doesn't perfectly match the book. See my last post.

And I'm not a robot that can only use instructions. I have and use curiosity too, and would like to save time if my assumption the lobe could be used the same as the marks to do the timing without having to take the cover back off is correct.

[juntjoo]

no,the compression might not vary much,bring number 1 to tdc compression,number 4 lobes should be sort of up and both level sort of at an even amount.

when the cam is timed slot forward and level as per the book your actually setting it at #4 compression,both lobes are down and #1 is at overlap,visa versa if you time that slot rearwards,with your finger over the plug hole on #1 feel the compression coming up watching the 1/4 T mark and stop it there,by rights the slot should be rearwards and both #4 lobes upwards on overlap.

Thank you!

[juntjoo]

no,the compression might not vary much,bring number 1 to tdc compression,number 4 lobes should be sort of up and both level sort of at an even amount.

when the cam is timed slot forward and level as per the book your actually setting it at #4 compression,both lobes are down and #1 is at overlap,visa versa if you time that slot rearwards,with your finger over the plug hole on #1 feel the compression coming up watching the 1/4 T mark and stop it there,by rights the slot should be rearwards and both #4 lobes upwards on overlap.

Yeah that's pretty much what I'm seeing. I'll just proceed from here...

[Bodi]

I'm unsure of what your question is. Marks on cam sprocket? I think your bike is like others, with two cam sprocket bolts. Unless the sprocket has an odd number of teeth/notches, it doesn't matter which way around it bolts on. I don't know if it does have an odd number: if it does, the cam and sprocket will be marked to show which way it should mount.
After that there's no more adjustability than moving the chain on the sprocket. Rotate the crank to the T mark specified in the manual. Rotate the cam until the end mark is as specified in the manual: usually it's a notch or line to be parallel to the head top, or sometimes vertical. With the sprocket at the correct position so the bolt holes line up (and marks aligned if there is an odd tooth count) slip the chain on and set the sprocket on its cam flange. If the bolts will go in then bolt it together, if it's a tooth off then go back and move the sprocket one tooth on the chain.
There is no easy way to tell if it's exactly right through the adjuster covers. If it's way out you won't be able to turn the crank over because the pistons will hit open valves: force it and those valves will be bent and destroyed. One tooth off should turn over without valve contact hand turning it over but they may crash at high RPM.
You can put a timing dial on the crank calibrated to 0 deg at TDC, put a dial indicator on a valve adjuster screw end, and measure lift as you turn the crank. Usually valves will open and close symmetrically with standard cams - exhaust will open any arbitrary amount the same rotation before BDC power stroke as the intake valves lift the same amount at the same crank angle before TDC exhaust stroke. If you can find a cam sheet, it will specify the timing. Exact lift at exact degrees is not so easy to measure... cam sheets use different criteria so getting the numbers to measure exactly as specified can be complicated. Some spec cam lift (which you can't measure from the adjuster hole), some spec valve lift (varies with tappet geometry) and for that some want zero lash, some want a specified lash clearance.

[bryanj]

Just to throw my spamner in 90psi is way too low

[juntjoo]

Just to throw my spamner in 90psi is way too low

90 on #2, the rest 120

[juntjoo]

Is this a normal sound? The water drop sound. Does it tell you anything significant? Idk what proper combustion looks like from the exhaust ports but I have seen spark in each one, not this attempt but others.

Currently checking the carbs. Spark looks good.

[dave500]

they make that noise without the pipes on its normal mate!

"Japanese water torture"?

[jgger]

Why do you insist on doing everything differently?
 There are manuals written with the proper procedures to do all this, you know?

 🍿😲

[juntjoo]

Thank you Bodi for all that info

[juntjoo]

they make that noise without the pipes on its normal mate!

"Japanese water torture"?

Good to know! Mate? Ah.. From Australia. Okay, I'll put the proper accent on you in my head.

[dave500]

good #$%*,just don't offer me a #$%*ing fosters or Victoria bitter beer!

just for you juntjoo

[juntjoo]

good #$%*,just don't offer me a #$%*ing fosters or Victoria bitter beer!


just for you juntjoo

Dave, those pics you took, are they of the left side of the cam? They must be cuz the lobes are downwards.

Did you just take them? Is that cam out and can you look real quick the right side, in relation to the mark level pointing forward, TDC compression stroke, as you noted, the lobes are slightly up and even... are they completely even? I'm just double checking, used a straw and my finger in #1 to make sure it's at TDC, and #4 lobes are partly upwards BUT my exhaust is slightly higher.

Pic shows where my timing mark goes when my make my #4 lobes perfectly even. That could be a tooth off if they're supposed to be perfectly even.

No rush or need. Just let me know if you can or not. I'm trying to avoid taking the cover off cuz I was having many oil leak issues with the cover months back and I just used fresh copper washers and a layer of gasket maker.

Also, how does this spark look? I've never changed my plugs and spark has always looked like this so I don't know what a weak spark looks like.

Thanks

[dave500]

that's the right hand side of the camshaft you can see the timing slot,pull your cover off and check your marks properly for #$%*s sake!

[juntjoo]

that's the right hand side of the camshaft you can see the timing slot,pull your cover off and check your marks properly for #$%*s sake!

You said it yourself!

"much,bring number 1 to tdc compression,number 4 lobes should be sort of up and both level sort of at an even amount."

Exactly as I have in front of me except the lobes aren't perfectly level.

I bet I'm a tooth off. K, I'm going in...

[Scott S]

 Spark looks good.

 You're making this way too hard. Set the T timing mark for 1/4 on the pointer in the center of that window, with #1 at TDC.
 Set the notch on the end of the cam at either 3 o'clock, level with the edge of the head. Forget about any dots or marks on the cam sprocket.
 If the holes on the sprocket don't line up with the holes in the cam when the cam is level and T mark is lined up, move the sprocket one tooth, NOT the cam and NOT the engine.
 Forget what the lobes look like. Use the T mark and the notch on the end of the cam.

[Scott S]

 This is a 550, but it's the same. First pic shows notch pointing forward/3 o'clock. From the RH side of the engine.
 Second pic shows what #1 lobes look like. From the LH side of the engine.

 Set #1 at TDC....with T mark at pointer.
 Set cam as pictured above e.
 Make sprocket match cam when engine and cam are in that position.

[juntjoo]

Okay got it. I was off a tooth! See pic. With cam mark horizontal I was there on the CS. I swear it wasn't that obvious before. Good lesson. I was just lucky last couple of times. Now I know how easy it is to miss it. I figured marks shifted and I was close enough I guess but now everything is lined up perfect(let's hope).

But suddenly the crank feels tighter. I've accidentally got the chain on but stuck on the crank so I don't want to be encountering another chain obstructing situation. With the crank sprockets, do you either get on right or wrong and your stuck or should I take it off and do it again? Am I making this more difficult? What can I say. I'm ignorant and I don't wanna mess anything up. Pat yourself on the back you can do this with one hand while solving a rubix cube in the other. Bravo. Thanks for your help though. I'm figuring this out. I just hope I remember in 6 months

I'm gonna keep putting it back on looking for a less tight feel in the crank until you guys tell me it should be tighter when on the right tooth. I wouldn't know why though

[juntjoo]

Ah! Loosen the chain tensioner bolt! In the morning. Thanks for your help and patience