How to Fit Yoshimura ST-1 CamsNOTE: This thread is also available to download as a PDF file from the Downloads (General) Section
This thread directly references fitting the Yoshi ST-1 cams, but broadly applies to any more extreme profiled cams in the 14 engine. This is not model specific, to my knowledge there's no difference across the models that affects this
First things first
1. Before stripping the motor down or reaching for the spanners, read these instructions together with the instructions you received from Yoshimura until you are sure about what you are about to do and the steps to be taken.
2. I've done this write up as a vague guide, and I'm doing it a few months after performing this procedure myself. There's every chance my memory has omitted some detail, if so, I can't be held responsible - this is a rough guide, not manufacturer’s instructions (see the workshop manual and cam instructions for those, they fully cover the job.
3. I think this is a detailed, yet fairly simple job. I'm not a trained mechanic but have replaced internals on a few bike engines before. You just have to be very methodical. Anyone who's fairly competent and confident with spanners should be able to manage this, so I'll rate it 3.5/5 for "how hard is it to do myself mate?" (1 being putting petrol in the tank - 5 being fitting new gears).
4. If you don't feel confident, get a mechanic who is.
5. Oh, one last thing... have fun, it's a nice job to perform
Things you should be aware of:
(a). The fueling will be off after fitting, and a PCIII and dyno setup is needed
(b). New cams will require running in
(c). You must check your shims after assembly, and it's quite likely your shims will need changing, especially on the intake side
(d). Not being funny here - the bike will pick up speed quicker in mid revs. Do consider uprating brakes and suspension first for safer riding (please)
(e). The Cam Journal Covers MUST be modified, to prevent the new profile cams hitting them and doing untold damage!
(f). This job will be easier on an empty tank - don't refuel just before you plan to do this
(g). You can fit the cams and perform all this without removing the engine from the frame (which is a bonus!)
(h). This is not a job that you should do over a few beers. Cams are best fitted when sober.
Things you really should have to hand before you start:
(a). Workshop manual
(b). At least half a day to perform the job
(c). Torque Wrench & a range of sockets, along with Allen keys, tray for storing all the bolts, selection of spanners and any other usual useful tools
(d). A fairly fine metal file
(e). Some fresh engine oil
(f). Some Moly grease (for prepping the cam lobes to be run in)
(g). A rear paddock stand is handy to level the bike and raise it a little, the centre stand would do
(h). Some instant gasket - to help re-fit the cam cover gasket (can be re-used so long as it's in good condition)
(i). Clean rags (Also some cleaner/polish/ACF50 is good to have around as you can clean up the top of the engine whilst you're accessing it
Ready? Here's roughly what you do:
1. Clean the bike first. Then remove seat & side panels
2. Disconnect fuel line & power couplings to underneath of tank.
3. Remove tank & place on blanket/cardboard to prevent damage Remove the rubber bungs from the frame that hold the tank (in case they fall into the engine)
4. Remove PAIR system (recommend you do the PAIR mod here and block off airbox outlet and use blanking plates on the engine side)
5. Clean top of engine to remove anything that could fall in, then disconnect and remove Cam Position sensor
6. Remove the Camchain tensioner from the rear side of the head, observing which way around it is as you remove it. It fits both ways, but must only go in the correct way - fiddly to get to and must come out straight or it can snag on the inside of the head
7. Disconnect and tie off the Plug caps & leads so they're out the way
8. Clean the bike of any debris that's around the top of the head, or anywhere over it. You don't want grit and other things landing on your exposed cams
Pause: Now have a cup of tea and something to eat. The next chunk should all be done in one hit to avoid leaving the engine exposed to dust and stupidity
REALLY, REALLY IMPORTANT NOTE: You MUST Follow the instructions in the workshop manual, and cross reference with the fitting instructions that come with the Cams for all the next steps
9. Remove all bolts, then remove the upper cover/cam cover from the engine, this will expose the cams. Be careful not to damage the gasket, and DO NOT pry anything. A simple, very light tap with a rubber mallet around the cam cover will loosen this enough to lift off by hand. If it doesn't move, you've overlooked a bolt.
10. You can now see the covers that retain and guide the camchain, and the camshafts. Carefully remove the camchain cover, making extra sure you don't lose the bolts inside the engine (particularly down the opening for the camchain). If you do lose something in there, unless you can recover it, it's potentially a full engine strip down which will easily take a day or two (engine out), and require more gaskets.
11. Camshaft Journal Covers coming out next. Note which goes where - they're all marked up. You remove them one at a time. Be aware that when you do get them off, the camshafts will be loose. This means they'll pop out of their journals, the camchain will come off/slip a few teeth, and your cam timing will go off... past the point of no return now!
12. Take a very long, clean screwdriver, or metal bar/pipe at least 10-12 inches in length. Slip this under the camchain, then remove each cam by lifting it out of the journals and towards the centre of the motor to slip it free of the tension from the chain. You screwdriver/bar is there to prevent the possibility of your cam chain falling into the motor and off the opposing wheel/cog at the base of the head.
13. Both cams are out. Fiddly job now. Remove the wheel/cog from each of your existing cams - these go onto your ST-1 cams. The bolts are 'you little ****er' tight, and you'll have fun figuring it out so I won't spoil this for you. Once off, fit them to your new cams, and ensure they're 'you little ****er' tight when you do so.. again, fun that. Just don't use a bloody vice to hold it! Note which wheel came from which cam and refit the same way around to match up for wear (easier to do one cam at a time - as in swap the intake one first, then exhaust after).
14. Half way there. Apply Moly grease to the journals and lobes of the new camshafts - the moly gets into the metal to protect, allowing them to bed in better.
15. Fit the new cams into place, ensuring you’re getting them in the right way around (intake on intake, exhaust on exhaust). Get that wrong and results cannot be predicted... but they probably aren't good.
16. Pick up your intake cam journal covers (the cover things with the holes in that you took off to let the original cams out). On the intake covers, file a deep groove into the depressed notches that are by the holes - according to Pops Yoshimura, these indents will be hit by your cams if left untouched. You're looking to lose about 3-4mm, as per the pictures in the cam instruction leaflet that's in the Yoshi box when delivered.
17. IMPORTANT: Observe the notes on aligning the timing marks on your camshaft wheels, and also on resetting the camchain correctly. You must count exactly the right number of camchain link pins between the two marks. Get that wrong, or do so when the markings are not aligned correctly and your cam timing will be out. I know that on a lot of engines that will introduce Mr Piston and Mr Valve.. and you then get known as "Mr Engine Rebuild" to your mates.
18. So, new cams in, cam timing set.. easy from here. Replace the Journal covers over both cams. Torque them down gently, alternating between the covers to lower the cams evenly (not one cover all the way in at a time). Use diagonally opposing bolts across each cover as you lower it, so as to lower the journal covers evenly too. Everything wants to go down straight an level, not one corner or part at a time. These will force the cams into place and gather some tension on the 'now correctly timed' area of the chain. The tensioner then removes the running slack in the rest of it later.
NOTE: NOW DOUBLE AND TRIPLE CHECK THAT YOUR TIMING IS RIGHT, AND YOU'VE GOT THE CAMS IN THE RIGHT SIDES OF THE MOTOR19. Replace Camchain Cover (don't lose those bolts into the motor!)
20. Pour fresh engine oil into the pocket of each cam lobe (recess of the head that holds the cam-lobe and shim), covering the lobe and the shims as deeply as the pockets allow. Ensure you get all of these or you'll start the motor with a dry cam, and that's not very friendly.
21. Now that you've observed the 3-part action of stage 20 to prevent wrecking the pistons, you can relax and continue
22. Replace the Camchain Tensioner, ensuring you get it the right way up (if its in right way up and upside down) - the teeth on the spring loaded shaft must face downwards. Wrong way round and there's a chance it could ratchet back in and let the camchain jump off the wheels whilst running (see previous point about Mr Piston and Mr Valve again). This is the fiddly little **** of a task that will likely take you 3-hours of skinned knuckle swearing - again, I won't spoil the fun, you'll figure it out (hint, use ring spanners)
23. Right, your back will probably be hurting from hunching over the motor. Camchain tensioner's bolted in, camchain's under tension, timing's correct, cam journal covers are in place. Brilliant, worst of it done. Quickly check your valve clearances, or take the bike to your dealer from them to do it (after you've assembled the bike obviously - cost around £70 for labour and swapping shims, or about £60 to buy shims yourself).
24. Replace the cam cover, using a little instant gasket to help seat it (and I mean a really thin smear, not a thick smear, or a bead of it you oil journal blocker!) observe guidelines for the order in which to torque it down, and correct torque settings. Replace Cam Position sensor too.
25. Reassemble everything else, according to the way it came apart - use the workshop manual or photos you took during disassembly if you can't remember.
26. Once all refitted and reconnected... stand up and beat your chest like the real man you are, you've just fitted racing cams to your 1402cc bike, without a mechanic!
27. Here, I loaded the "Akra system and Yoshi ST1 Cams" PowerCommander map onto my PCII. Not perfect as mine's a Yoshi system, but it's closer than stock fueling. Please get to a Dyno ASAP for setup
28. Start the motor (don't rev it!!!!), and listen to the engine for knocks or nasty noises. You'll hear the camchain whirr, and the ticking of the cams. You shouldn't hear anything else nasty. If you do stop, disassemble for idiot checks, or hand it to a competent mechanic.. then hand your spanners into the police station and have yourself put on the offenders list of people never to buy bikes from.
29. Observe the detailed bedding in procedure for the cams that are in the instructions they came with, it outlines rev limits and distances they're imposed for. Don't go out and hammer it you loon!
Additional comments made after the above was postedResponse-1I have just finished mine this evening I reckon it took 5 hours taking it easy. The bike only has 1100 miles on it so nothing was corroded on.
I took off the coils for better access and undid the 2 bolts holding the oil cooler on so it can be pushed forward a little for better clearance for removing the cam cover.
The only extra I did was put thread lock on the bolts holding the cam gears. You can put the cam gears in the vice for undoing and tightening using soft jaws that’s the best way I could find to hold them.
Before starting and putting the tank back on I unplugged the coils and cranked it over on the starter for a while to get the oil pressure up.
I did the inlet cam first and put the chain back on and held it in place with a cable tie so when installing the exhaust cam I only had to count 24 rollers so it was in the correct place.
The cam journals cover were really tight I couldn’t them pull the off so I put a drift down one of the mounting holes that was the exact same size one little wiggle and it was loose don’t lose the little dowels that are on the covers put them straight back in the hole on the engine.
I must have checked the alignment of the cams and cam chain about 5 times just to make sure.
Response from Topic AuthorThere's a pic of where to modify them in the Yoshi instructions that come with the cams (see end of this article). I used a medium/fine grade file to modify the covers. In the covers, there is a hole and indent either side. On the inside of the cover, it's that indent you're filing down to gain more lobe clearance.
Response-2Most aftermarket cam makers state you mustn't let the engine idle for an excessive amount of time. That's because the cam lobes get a limited amount of oil at idle. A few revs raises the pressure to give more fed oil and splash oil.
Lobes are "soft" when new and it is the running in that hardens them.
If you go too hard too soon you stand a good chance of knocking a lobe off or severely damaging one by flattening it.
Response-3I think you will find the cams are case hardened then ground to size, the reason for running in is so that the new cam gradually wears its self into the new bearing material
Response-4Here are the pictures. May be quantity is a little bit more than you need
Response-5I'd like to point out that every engine is individual with different clearances and when changing to high-lift cams you have to check all the spots where the clearances might be too small.
In my engine the intake covers were good, only one spot had to be filed but several valve holes were too close to the cam and the cam hit the valve head itself. It's very important to check that the cams are not touching anything else but the valve caps and that’s a bit hard to do if you have the valve head attached in motor (with the valve caps in place).
Just wanted to point out that it's very important to check all the possible spots where the cam might get in touch to avoid engine break down.
