Diesel Do

[edwardsa]

Hi Gents

Please can I pick your brains regarding this phenomenon. I have just bought a 1995 HW99 from a dealer who I asked to check the output (it had been 'tuned')which was 673 fps with hobbys = 11.99 ft lbs. It has since started dieseling a lot, after 150 shots it stopped, then after another 50 started again. Now it's had 250 through no smoke but the shooter next to me said he could smell it still was. It cocks & shoots smoothly & accurately so hopefully won't need anything too drastic doing.

Any similar experiences would be helpful, thanks Andy.

[countryboy]

It does rather sound like inappropriate lube has been used in the cylinder, and has now burnt off. I would be sorely tempted to strip, 're-lube with some moly grease and polish the cylinder / piston as necessary. I have never done a 99 , but plenty of guides out there. Never as daunting as you may think.

[edwardsa]

Thanks for that, I could take it back if I had to (50 mile round trip) but if there is anything I could do to save this it would be better. This working for a living gets in the way of everything.

[TonyL]

It does rather sound like inappropriate lube has been used in the cylinder, and has now burnt off. I would be sorely tempted to strip, 're-lube with some moly grease and polish the cylinder / piston as necessary. I have never done a 99 , but plenty of guides out there. Never as daunting as you may think.

As above.

It may be that all will now be perfectly fine and that any excess lube will have been burned off....But if it was over-enthusiastically lubed, some more line may well migrate forward again. Better to strip, degrease and re-lube if OP can.

[TonyL]

I have just bought a 1995 HW99 from a dealer who I asked to check the output (it had been 'tuned')which was 673 fps with hobbys = 11.99 ft lbs.

Is the 11.99 the figure the dealer gave you, or did he "check" it and you've later checked? Either way, it really needs tweaking down. Even at 11.7 you'd be sailing close and it wouldn't take much to send it over. For a long time, the general belief was that a springer would develop higher muzzle energies with a lighter pellet. And this may well be the case. But it might make more power with other types of pellet.

If you're happy with the gun in terms of how it shoots, accuracy, handling etc and you've started to get attached, I wouldn't take it back, but would be stripping and de tuning a bit

[edwardsa]

Thanks Tony , he disappeared into the back of the shop and came back with his calculator. In hindsight perhaps I should have asked him to try a few different weight pellets. My F1 chrony seems to record about 10fps higher than others and is now fluctuating in the 660-670 range so should be ok, if only I could watch someone stripping down, there's only so much you can get from youtube.

[countryboy]

Just found stripdown guide on airgun magazine on Google.I don't know how to do links, but easy enough to find. Enjoy your first fettle.

[rabbitwrecker]

Is the 11.99 the figure the dealer gave you, or did he "check" it and you've later checked? Either way, it really needs tweaking down. Even at 11.7 you'd be sailing close and it wouldn't take much to send it over. For a long time, the general belief was that a springer would develop higher muzzle energies with a lighter pellet. And this may well be the case. But it might make more power with other types of pellet.

I think you might be wise to tweak it down somewhat below 11.7 ft/lbs. If the three Weihrauchs that I've been using lately are anything to go by, 11.7 ft/lbs with RWS Hobby will likely give you closer to 13 ft/lbs with JSB RS...

.177 HW99s - Hobby = 10.7 ft/lbs. JSB RS = 11.65 ft/lbs.
.22 HW80 - Hobby = 11.35 ft/lbs. JSB RS = 12.5 ft/lbs. (Yes, it's been sorted, now doing 11.2 ft/lbs with RS).

[oliver13]

I'd just strip it down, swill it out with brake cleaner & re lube appropriately. It's clear it's dieseling a bit & that really needs to be sorted.

[Lightning1981]

Thanks Tony , he disappeared into the back of the shop and came back with his calculator. In hindsight perhaps I should have asked him to try a few different weight pellets. My F1 chrony seems to record about 10fps higher than others and is now fluctuating in the 660-670 range so should be ok, if only I could watch someone stripping down, there's only so much you can get from youtube.

If you want a strip down guide I have one from a magazine that a kind member emailed to me that I can forward to you. I had never stripped a springer before and the 99s really is easy to work on and I would do it again. If you want a copy pm me your email address and I will get it sent to you.
Dave

[slugger]

if you cant work out how to strip a basic springer, you are clearly not a man ! you should be re-classified as a 'girls-blouse' and put post-haste into the kitchen where you belong..
seriously tho, get yourself on youtube, its easy, anyone can do it. im blind , deaf , and have no fingers left after dissasembling what i thought was an air-arms prosport........ was actually a gas main in the garden [who knew right] but even i can strip and relube a springer, and therefore dont have to be locked in the kitchen with the fanny-blankets

[Chilled]

I recently purchased my first rifle in the form of a HW50/HW99, and had never so much as mounted a scope.

I wanted to clean and fit a Tinbum kit on a straight from factory HW50 and found it rather easy!

Follow this video and you won't go wrong, in fact look through his other videos as there's loads too learn in them, cleaning etc.

https://www.youtube.com/watch?v=-rCKzgY_-x4

[shauny]

if its "dealer tuned" its prob stuffed full of grease, hence the dieselling,
but it also sounds like you need to lop a coil or two from the spring,running
a wee bit close to confiscated gun.

[davymole]

as loads have previously said stripping is an easy task just follow the utube video,s only thing you will need are a punch for the trigger pins ,watch you collect the safety pin and the spring, replace the rear trigger screw as it saves looking later for the captive bolt,a shortened allen key to pop out the four tangs and then a rubber to place on the bottom whilst you press down and twist off the end block, not to difficult and a easy job putting back together as for lube little is best I use just a small artists paint brush.

[averageplinker]

I suggest a strip and relube and rechrono before turning it down/looping off a coil. If it is dieselling this may be enough to get the power down enough to be safely within 12ftlbs.

One other thing, if it has been dieselling give the barrel a few pull throughs to clean it!