GS700E_Top End Rebuild_Stuck At Camshaft Install

[Sean]

First I'd like to say how invaluable this forum has been and is the only way I have been able to get as far as I have on this rebuild. Thank you guys for all your knowledge, it's much appreciated.

Now to business, last summer I decided to get back into riding after totaling my 919 and breaking 6 ribs in April of 2012. After doing a bunch of googling I found the GS700 and fell in love with the style. Ended up buying one in late July (in hindsight paid way too much) and it ran decent for about 1,100 miles at which point there was pretty much no power across the whole throttle range. Fast forward to this spring when I started troubleshooting it. At first I was focused on the carbs but after tearing apart and cleaning twice realized there was a much bigger problem. That's about the time I came across The GSResources. I thoroughly read all of the introductory info and dug into as many threads as I could. The conclusion I came to was that I had to check my compression and it was not good at all. I checked and adjusted the valve clearances to spec but it made zero difference. As a side note I work at the GM tech training center and was also getting advice from the instructors on next steps. One tech suggested I check the compression after pouring some oil in the cylinders, it went way up so at that point I began dismantling the top end figuring there was an issue with the rings. I had been told that the bike did some sitting and read in a thread that sitting can lead to ring problems. Engine came apart with no problems, quite a bit of carbon build up on the pistons and valves of course. After a ton more research I ended up buying a used head, pistons and block off ebay, along with every gasket and little part that should be replaced for a rebuild. I took the engine components to a friend's Dad who works at a motorcycle shop, he inspected the parts told me that one of journals was cracked on the block I bought but the pistons were in better shape and the head I bought was also in better shape. He honed the journals on the original block for me and offered to help assemble but has just been too busy to make it over, so he installed the new rings for me and sent me home with my parts. Two months later I finally decided to stop procrastinating and attempt the rebuild myself. I managed to get the pistons in the journals and installed the head on top of the block. Now I'm at the cams, I did mark the chain and cam gears with a sharpie so I know where the teeth line up but have no idea how to actually get both cams in and seated properly. Tried to do so last night but realized that there is something I'm not doing right as the chain will not allow the second cam to make it into it's seat. Looked in the forums for a couple of hours and could not find any specific details on how to install. Did I overlook a guide or thread somewhere? I've got so much time and money in this I really don't want to mess it up so any help/advice would be greatly appreciated. Heck if anyone wants to stop by to help me zip this up beer and dinner is on me :welcoming:

Thanks in advance!
Sean P Cook

P.S. I promise to post images, I have some of the engine internals and will take more beauty shots once it's running.

 

[eil]

Welcome, fellow Michigander! I'm in Ypsi Arbor.

the chain will not allow the second cam to make it into it's seat.

Are you following the instructions in the service manual? It should be a matter of setting the cam shaft in place on the journals, clamp it down with vice grips, and then install the caps. Paying some attention to the timing so you don't clamp a valve down into a piston, of course.

Normally I'd be happy to scoot on over to act as a second set of eyes but my next two weeks are busy busy.

 

[Sean]

Hey Charles! Very familiar with Ypsi/Arbor that's where I go to brew beer as well as where my friends Dad is that helped me with the cylinders.

From what I saw in the owners manual it says to take it to an authorized dealer. The service manual supplement covers valve clearance adjustment but nothing about camshaft removal or installation. I'm going to approach it again tonight when I get home, just feeling a little apprehensive as this is the first engine I've ever had open like this. If I don't have it running in the next couple weeks, which I really hope I do, I'll have to send you a line for some help.

Sean

 

[williampkerr]

Have you removed the cam chain tensioner yet?

 

[2BRacing]

Do you have the proper OEM service manual? It definitely has detailed instructions for fitting camshafts and setting the valve timing. Look here for the info: http://members.dslextreme.com/users/bikecliff/

EDIT: Just looked myself on BassCliff at the 700 Supplementary manual you mentioned, and you are right, only valve clearance measurement in that one (no wonder it is only a few pages). However, instructions on first or second page say you must also refer to the 750 manual for complete information. It is definitely in there.

 

[Sean]

Have you removed the cam chain tensioner yet?

I had it removed but just re-installed it last night. I'm going to look into the 750 manual, thanks for that lead.

 

[Sean]

Found the details in the 750 manual. Will attempt when I get home tonight and let you know how it goes. Thanks for the tip 2BRacing.

 

[2BRacing]

You're welcome! I suggest you first spend some time reading through the procedure (even a couple of times) to make sure you understand everything. If you do not understand, ask on here.

Then just take your time and do each step by the book. Make sure you get the 1.4 I T mark lined up correctly (check piston 1 is at at TDC). Lubricate the cam journals (bearings). Tighten the cam bearing caps down evenly in small increments at a time, moving from left to right across the cam chain tunnel and criss-cross across each cam cap (you can clamp the exhaust cam down with a vice grip, so that the valves under cam lobes are compressed and do not exert force on the cam, making the caps difficult to tighten down). Do not force anything and make sure the caps locate properly on their locating dowels. I have cracked cam caps by not following my own advice! Remember that the cam chain pin at the arrow of the exhaust cam is pin number 1 (and not 0), and count the correct number of pins to the arrow on the inlet cam.

When everything has been tightened down, turn the engine (with spark plugs removed) at 19 mm bolt on right side a few times and check that all marks/arrows/pins are still correct, before turning the engine over on the starter motor.

 

[Sean]

Make sure you get the 1.4 I T mark lined up correctly (check piston 1 is at at TDC).

All very helpful info. Just to clarify when the T is lined up with the 1 4 the engine is at TDC?

 

[Sean]

Also what is this image telling me? It's in the GS700 Supplementary Manual.

 

[2BRacing]

All very helpful info. Just to clarify when the T is lined up with the 1 4 the engine is at TDC?
View attachment 36005

No, the position in your photo is not correct for TDC for numbers 1 and 4 pistons.

I have drawn the correct orientation in on your photo below (excuse my poor skills with photo editing apps!)



The correct orientation mark on the engine case is at about 9 o'clock position (that thickened portion of the engine case). You should see a line scribed into the engine case at that thickened portion. That is the correct index mark for TDC for cylinders 1 and 4. The T mark on the rotor must be at the position I marked in red, to line up with the index mark on the engine case. [in other words, in your original photo, you have turned the crank too far clockwise]. You can check this by removing all the spark plugs and turning the engine clockwise with a 19 spanner at right side, while holding a screwdriver into the spark plug hole of cylinder 4. You will soon verify when the piston has reached top dead centre (the top of its stroke before it changes direction and starts to move down again). At this point, the T mark on the rotor must be at about 9 o'clock to align with the index mark on the engine case at about 9 o'clock position.

The other image you refer to from the supplementary manual is the valve timing diagram, showing the number of degrees the inlet and exhaust valves open and close before or after Top Dead Centre (TDC). You do not have to worry about that at all in your assembly procedure, because once you have set up your exhaust and inlet cam according to the correct orientations and with 20 chain pins between the arrows as shown in the full version of the manual (by the way, the very large file on BassCliff site for the 750E/ES is a much clearer one than the other (smaller file) 750 manual) - look on pages 3-76 to 3-80), those valve opening and closing angles will be as close to correct as a standard production engine can be. Guys who race will use adjustable sprockets on the cams to "dial in" the cams to the exact number of degrees they want for their specific purpose.

 

[Sean]

So after some more reading and getting my hands on it last night I did figure out the positioning for TDC (it all came together in my head). Alas I could still not get the cam to drop into place. The manual makes it sound super simple "Engage the chain with intake sprocket, locating the 20th pin at and above the arrow marked "3" on the intake sprocket". I tried to re-approach it 4 or 5 times and stared at it for what felt like hours, no vice grips but I did install the bearings at one point on the exhaust cam to see if it would give me any extra leeway, it didn't seem to give me much at all. I feel like there is something extremely simple that I am over looking. As you can see in the photo there is still about an inch to go until it drops into the journals and I counted the pins about a gajillion times so definitely 20 pins away. There's got to be something I'm not doing, right? What could it be?

 

[2BRacing]

You have removed the cam chain tensioner, right? There will not be enough slack in the chain if the tensioner is still installed.

Pull up on both sides of the chain to make sure that some links have not bunched up under the crank sprocket

 

[Sean]

Yep cam chain tensioner is out. I thought about the links being under the crankshaft sprocket, tried to pull up on the chain. I'm thinking I should unbolt the head remove the front guide and try to pull it up then re-install.

 

[2BRacing]

Before going to the length of removing the head, first try to make sure that the chain has not bunched up under the crankshaft sprocket. However, you need a helper (a helping hand or two!). Remove the cams, and have your helper put both hands under the cam chain at both the exhaust side and inlet side, while also pulling apart in order to keep the chain tight (in the same way the chain is pulled tight when it is over both cams).

With all the sparkplugs removed, first turn the engine backwards for about one turn at the 19mm bolt at right side of engine, and then forwards for about one turn, while still keeping the chain tight. The aim is to make sure that the chain is stretched tightly around the crankshaft sprocket without any links hanging loose or bunched up, or stuck at the bottom of the front guide. Once backward and forward motion of the crankshaft can be positively felt by the person holding the chain, turn the crankshaft to align the 1&4 TDC marks, and insert the exhaust cam while still holding the chain tight at both ends to prevent it getting slack and going under the crankshaft sprocket.

I have had success with the above procedure, but maybe others here will be able to provide other solutions that have worked for them.

 

[Sean]

Woohoo! I made some progress! Took the front guide out and pulled up on the chain then put the cams in no problem. The only thing I'm wondering about now is the position of the notches on the right side of the cams. They are suppose to point either away from each other or towards each other, as you can see from the photo they are pointing in the same direction. How could this be? I remember when adjusting my valves before ever taking apart the engine that they matched what the guide said. And the markings on the sprocket are correct the 2 and the 3 arrow point directly up at the same time.

 

[2BRacing]

Well done! Now for the last hurdle: the notches on the cams.

Check that the exhaust cam has "EX" identification letters on it, and inlet cam has "IN" letters on it. Have you not mixed up the cams from old / new cylinder heads by mistake? Did you remove the cam sprockets? If you did, did you re-install them correctly?

When setup correctly, the notches on both cams must point inwards towards each other.

 

[Sean]

Hmmm the EX and the IN are on the right ones and there is only one set of cams so no mixing up there. I do remember unbolting the sprocket on the IN while disassembling thinking that would aid in their removal so that must be the issue. When I get a chance I will check that out and let you know how it goes. Almost there!

 

[2BRacing]

It looks like your inlet cam sprocket is not correctly positioned on the inlet cam.

With crank set so that TDC mark for 1.4 lines up with reference mark on engine case as in previous photo, arrow 1 on exhaust cam must point to the front of the bike and be about level with the head surface. At this time, arrow 2 will point upwards, and the notch at the end of the cam will face towards the rear of the bike. Looks like your exhaust cam is correct.

With inlet cam turned so that notch faces forwards towards notch of exhaust cam, the sprocket must have arrow 3 pointing straight up. The lobe of number 4 intake valve should be pointing back towards the carbs, and not towards the front.

Remember to get the 20 pins between arrows 2 and 3 correct, with the pin over arrow 2 being counted as pin number one.

After everything has been tightened down, turn the motor a few turns clockwise and verify that 1.4 TDC crank setting has correct cam orientation as described above.

Check valve clearances by following the manual's procedure for camshaft orientation and measurement of corresponding valve clearances.

Now you should be good to go!

 

[Sean]

You were absolutely right. That was an easy fix. Almost done adjusting the valves, once that's complete I should have it all back together in no time. Thank you thank you for helping me get past those speed bumps. Do you know if these carbs need to be vacuum synced or will a bench sync do the job? I've been trying to find info on how to do the vacuum sync but haven't came across anything.