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1982 Yamaha Seca 650 (Project)

Discussion in 'XJ Technical Chat' started by firebane, Jun 27, 2019.

  1. firebane

    firebane Active Member

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    [​IMG]
    I figured as I've posted a few "help" questions and been sort of posting within the "what did you do" thread that I'd make a small thread of the bike I picked up last year and the enjoyment and not so much enjoyment that I've had with the bike.

    This is a Canadian version Seca that has 52,000km on it and for the most part runs well and has given me zero issues. When I got the bike it never seemed to quite run right or "steer" right so it became a mission for me to start doing things and fixing and correcting on the bike.

    My first course of action was to figure out why it wasn't steering right and I found out pretty quick when I tried to change the brake pads that the right fork tube had a VERY substantial bend in it (https://www.xjbikes.com/forums/threads/front-wheel-brakes-82-xj650r.119773/). Found a great shop in the City I work in with a great mechanic who is capable of working on these bikes and $300 later for machine work, new pads and fork oil the fork tube was straight and the bike tracked better.

    This was sort of the end and near the end of the season and I got busy and didn't too much to the bike so it got parked and I started looking towards the other things that needed to be done.

    Last month I started to take on the project of finding a good clean airbox with lid and found a guy in town who had one but turned out to be for a 750 not a 650 (https://www.xjbikes.com/forums/threads/airbox-to-carb-boots.124375/) so I had to find another and sourced one up here in the Great North and got it ordered and shipped. Got that installed and one step closer to the bike running better.

    Once I got that all sorted it was getting the bike going again and got it started and running but still noticed around 6500-7000rpm the bike would just really stop accelerating and not want to move. So I then moved onto more troubleshooting and that is when I found out the bike was using resistor plugs and caps so the next order of business was to get that ordered and sorted. Unfortunately no shop in town stocks the original style plugs and they all want to sell you the resistor type so online I went to trusty Fortnine and ordered proper plugs and caps and now awaiting for that to arrive.

    As an FYI cap #1 measured out at 7.9ohms and the rest were within normal spec.

    I then moved to the small oil leak at the front of the bike and decided it was time to source an oil cooler for the bike and luckily I found another GREAT shop up here in the Great North and was able to order the cooler and adapter and get that coming to me and once that arrives I will install.

    I also took a look at the coils and measured those out and found while the primaries on both were on the very upper end of spec the secondaries were still quite reasonable, so I'll be keeping an eye on those and if need to I'll either replace or get Dyna coils.

    I'll be moving onto doing a valve check here in the next day or two and seeing where those are.
     
  2. tradmedic

    tradmedic Member

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    I'm from Canuckistan as well, Mississauga (for now)and once I get my maxim 1100 all up to snuff, my 650 seca will be the next project bike. It was my first bike, so it holds a special place for me. I'll be following your progress. Where abouts is local for you? I've ordered from xj4ever for the hard to find stuff or the value of one-stop shopping, it would be great to find somewhere up here for the odds and ends.
     
  3. firebane

    firebane Active Member

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    Most of my parts come from sourcing locally from the shops, ebay or a new one I found in Ontario called Hoop Rider. Not sure how long they have been around but its where I found my airbox and oil cooler setup from and their prices are pretty reasonable.

    I've looked at xj4ever for stuff but unfortunately with the crappy exchange rate and crazy shipping rates it has me looking for alternative sources. As an example I need to replace my drain bowl screws and I'd like to order the allan head versions but after the exchange and shipping I can just make them for a few dollars in my garage.
     
  4. firebane

    firebane Active Member

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    Well changes the plugs and decided to change mixture screws to 3 turns and now it's breaking up around 5,000 rpm.

    Can too little or too much fuel cause this breaking up?

    I plan to check valves in the next couple of days and look into doing a sync too.
     
  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Yes, fueling can cause that. So can several other things.

    Have valve clearances been checked?

    Idle mixture won't affect fueling at 5,000 RPM significantly, and 3 turns out is only a tiny bit rich.

    Have the carbs been broken down and properly serviced?

    Despit changing the plugs to non-resistor there could be an ignition issue. Have you cecked the reisitances of the coils, and removed the spark plug caps from the wires to check for corrosion?
     
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  6. firebane

    firebane Active Member

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    Coils were checked and both primary and secondary are in spec

    Caps and plugs are brand new as of today

    As I said valves will be checked in the next couple of days

    Haven't even looked at the carbs gets, but I have read a few things that I will try when it breaks up.
     
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  7. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    90% of running issues are due to carbs that have not been to church.
    99% are due to people (not you) who swear that they already cleaned the carbs and everything is fine on that end.

    IN THE CHURCH OF CLEAN
     
  8. firebane

    firebane Active Member

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    Oh I am doing my best to not get into the carbs. Seeing that I will have a challenge just getting the float bowl screws out lol.
     
  9. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    There really is no option if you want it to run right. If the float bowl screws are stuck that's a sure sign that the carbs have never been touched.
     
  10. firebane

    firebane Active Member

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    Oh.. they have been touched... and touched... and touched.. and they look like the carcass of a dead bird after a few wolves had lunch.
     
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  11. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    I meant properly. Like a prom date.
     
  12. firebane

    firebane Active Member

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    So raining out so not much riding happening tonight.. but did a couple quick things. I upped the spark plug gap from .025 to .028 as per a finding on Chacals site.

    While I had the plugs out I figured I'd do a compression check...

    #1 = 100 psi
    #2 = 90 psi
    #3 = 90 psi
    #4 = 100psi

    Now I know that valve clearance plays a role in this and being that I need to do that still.. My concern is that will it be a realistic thought I can gain 28 psi for #1 and #4 and gain 38 psi for #2 and #3? As 128 psi is the minimum for these engines...

    This bike also has like 55,000km (Canadian) on it.. so... yeah.

    Thoughts?
     
  13. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    First thought is make sure your compression gauge reads true.
    Second thought is to make sure tht you account for local altitued (if needed).
    Third thought is to make sure that you are following the specified procedure (throttle held open, engine cold).

    Valve clearances do play a significant role in compression readings. Keep in mind that when an engine sits for an extended period of time there will be at least two cylinders with one valve open. That allows moisture to accumulate, eventually washing some of the oil away from the compression rings. It's common for engines that have sat to have rings that are a bit sticky, or slightly corroded. Usually runing the engine for a good while will free things up and compression will improve. Your numbers (if accurate) are not so low that you should be concerned at this time.


    Your bike has low miles.
     
  14. MattiThundrrr

    MattiThundrrr Not a guru

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    K-moe has never been to prom with Matti.
     
  15. firebane

    firebane Active Member

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    Did a clearance check today.. And based off the spec sheet of 0.004-0.006 on the intake and 0.006-0.008 on the exhaust here is where I sit...

    #1 - Ex: 0.006 / In: 0.005

    #2 - Ex: 0.006 / In: 0.005

    #3 - Ex: 0.007 / In: 0.004

    #4 - Ex: 0.006 / In: 0.004

    While the majority are on the tighter end of the spectrum it looks like for this season at least I would leave the valves alone. Next season though.. well probably time to do some shims...
     
  16. firebane

    firebane Active Member

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    Sometimes its the small victories to offset the ugly ones :D

    Was able to find a OEM seat/helmet lock with key.

    [​IMG]
    [​IMG]
     
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  17. ecologito

    ecologito Well-Known Member

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    Any carb cleaning/ setting may be a moot point until you check your valve clearances.
     
  18. firebane

    firebane Active Member

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    Read my posts lol. I posted the numbers.
     
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  19. ecologito

    ecologito Well-Known Member

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    Somehow I missed the post while looking at the thread on my phone, carry on. I am following your progress.

    Looking forward to it,
     
  20. firebane

    firebane Active Member

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    Alright got the bike out tonight for some testing.

    Bike still breaks up around 6,000rpm and just does not pull through. Tried adding some choke, switching to prime and res and nothing changes.

    Thinking TCI

    Noticed also and it didn't do this when the pods were on the bike that it will idle high up to 3000-4000rpm when at a light.

    I know it needs a carb sync and its running lean because of this so time to see where air leaks maybe.
     

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