Got one on the way. Don't think I'll need to replace anything else given the KMS so I'll take a gamble and lap in a new valve. Longest wait is the parts. Aint gonna touch any of the others, the old adage if it aint broke dont fix it probably applies!
Completely agree with your thought process, if it ain't broke...don't fix it !!! Having said that once your new gadget arrives it probably wouldn't be a bad idea to de-coke the other valves and have peace of mind.
Hmm not having much luck taking the carbon off with threebond. Any tips? It will take some of the surface stuff off pretty well but the hard cakey stuff I left it to soak for a bit and not really coming off.
Leave it on for awhile and give it a help along with a tooth brush .... I just reapply the run off in the container with the brush when Ive done carbs and pistons Gloves help as it gets in your skin and stinks
Quick update, got the replacement valve direct from Honda in 48 hrs ($29.95) but still awaiting the valve spring compressor kit. Looks like it will be next weekend now as I didn't get it by today. Pretty keen to rip into it though, get this thing going.
Your a more patient man than me Joker...lol. Id be modifyiing somethin to get that valve out. Ive used a G-Clamp and a socket with a slot cut out of it before...Worked well, hahaha.
Patience is a virtue....so it is said!! Trouble is when you've got the "PART" you just want to get going
Yeh I have stopped myself from using a few backyard tricks I know about to get the valve out. Would rather do it legit as this is a good condition bike that I'm hoping to flog for moderate coin in order to invest in FZR upgrades lol
Mate had pretty much the same issues with a spada i was trying to do up. Found that there was old fuel in the system so would not ignite no matter what i did, had to push start it over and over to get the fuel to pass through but eventually it started up and ran fine. The smell from the fuel was sickly sweet and stayed for weeks if i spilled some. Hope this helps
Progress again!! This $20 fleabay spring compressor was worth the investment. Easy as pie. Yep, valve is just a little bit rooted... Seat looks OK which is good news. One of my favourite tools, kept this after the kids moved off bottles... use it heaps haha. Bit of threebond down the hole... Now the lapping. When I bought the tool & paste it comes with two grades (bought from REPCO). A knowledgeable mate informed me not to use the coarse paste (pretty much ever) but to work with the fine paste. So on that alone I took his advice, I haven't really done it before but it seems simple enough. I suppose working with the finer paste probably makes sense as it lowers the risk of over doing it or something... The tool I got from supacrap auto at some stage, the rubber is already perishing but it was just enough to get the job done. Put the suction cup on the valve, wind it back and forth and now and then pull it up and spin it so you're not always working in the same place. Here is the end result on the valve and seat: Just a question for the more experienced parties, the silver "tapered" section of the valve should I lap it so it is completely "grey"? It's about 95% grey at the moment, it starts off in the middle section (you can tell because the grey section contrasts with the shiny new bits) and as you keep going eventually the grey "band" gets wider until all the shiny section is pretty much gone. My logic says it should all be grey because that's the mating surface of the valve to the seat so you want it to have a good firm connection, but thought I'd check for other opinions just in case I'm wrong Haven't started the rebuild just yet, will start to piece it together maybe during the week and work it into the weekend.
Service manual should contain the correct angles and measurements for cutting the valves and the seats. If it's a new valve and the seat is OK, just lap the valve face and the seat with the fine paste, wipe it all away, and you're good to go. Did it on the fizzer with all the original valves and seats.
Yeh that's what I've done. It's how much lapping that is the question. The angled part of the valve is the mating face, my question is should the entire angled part be lapped or should it just be a tiny thin band in the centre of the angled part. The service manual talks about 2mm service limit with the face of the valve mating face somewhere between 1.0-1.2mm. That says to me the width of the band should be that, but that also seems quite small, very small in fact. I'm not sure how to accurately measure it, but I suppose I can always reinstall the valve and leak test it to see how it has gone. The manual is translated but pretty poor english to the explanations aren't great.
It's a small engine. Funnily enough, a smaller valve seating area is actually good. As the valves and seats wear down the mating surface area increases. Recutting the valves and seats sets surface area back to standard. Or at least, that's what I was taught at TAFE.
What you've done is about right. The whole of the seat face does not need to be in contact as Linkin said, they wear in. The seat width is quoted at 1.2mm? Leave it at that as going further you are effectively 'wearing' the seat. Exhaust seats are set at a width so they will transfer heat to the head, but without holding too much heat and burning the valve. If it holds fuel then it is done. Wash the grinding past out with petrol/kero, then wash it and the whole head with detergent to get ALL the grit out.
Bit more fiddling today, leak test - the valve weeps ever so slightly with petrol. Hmm. Tested the other ones - all the same. I lapped the valve slightly more to get rid of a little bit of pitting I spotted in the seat but pretty much the same afterwards when it came to the leak test. I've left it like that because I wonder if it's worth gambling with. The low viscosity of petrol may bias the test a bit... do these things need to be 100% leak proof? I'm kinda hesitant to lap it even more and considering it's done such low kms I wonder if it will wear in a bit on its own. Compression should be much better now, if in spec maybe not worry about it?
Do a compression test and find out... I wouldn't worry about it. The fizzer engine had every single valve leaking petrol when testing, before lapping the valves. It was running on a blown head and leaky valves, with out of spec valve clearances... it could be hard to start but it still ran and had decent power after doing the cam chain.
Yeh I was leaning towards that. compression should be 5 times better now (I hope). Will throw the head back on when I have time and see how we go.